Limerence is a state of mind resulting from romantic feelings for another person. It typically involves intrusive and melancholic thoughts, or tragic concerns for the object of one's affection, along with a desire for the reciprocation of one's feelings and to form a relationship with the object of love.

Psychologist Dorothy Tennov coined the term "limerence" as an alteration of "amorance" without other etymologies to describe a concept that had grown out of her work in the 1960s, when she interviewed over 500 people on the topic of love. In her book Love and Limerence, she writes that "to be in a state of limerence is to feel what is usually termed 'being in love.'" She coined the term to disambiguate the state from other less-overwhelming emotions, and to avoid the implication that those who do not experience it are not capable of experiencing love.

According to Tennov and others, limerence can be considered romantic love, passionate love, infatuation, lovesickness or even love madness. It is also sometimes compared to a crush, but contrasted as being much more intense.

Love and Limerence has been called the seminal work on romantic love. Anthropologist and author Helen Fisher wrote that data collection on romantic attraction started with Tennov collecting survey results, diaries, and other personal accounts. Fisher, who knew Tennov and corresponded with her, has commented that Tennov's concept had a sad component to it.

Limerence is associated with dopamine reward circuits in the brain. The early stage of romantic love has been called an altered mental state and compared to a behavioral addiction or an addiction to a person. Brain scans suggest that people experience motivational salience in response to a loved one. A long-running theory also compared the associated intrusive thinking to obsessive-compulsive disorder with a hypothesis that this is related to lowered serotonin levels in the brain, but the experimental evidence for that is ambiguous.

Dorothy Tennov's concept represents a scientific attempt at studying the nature of romantic love. She identified a suite of psychological traits associated with being in love, which she called limerence. Other authors have also considered limerence to be an emotional and motivational state for focusing attention on a preferred mating partner or an attachment process.

Joe Beam calls limerence the feeling of being madly in love. Nicky Hayes describes it as "a kind of infatuated, all-absorbing passion", the type of love Dante felt towards Beatrice or that of Romeo and Juliet. It is this unfulfilled, intense longing for the other person which defines limerence, where the individual becomes "more or less obsessed by that person and spends much of their time fantasising about them". Hayes suggests that "it is the unobtainable nature of the goal which makes the feeling so powerful", and occasional, intermittent reinforcement may be required to support the underlying feelings.

Severus Snape's love for Lily Evans, the mother of Harry Potter, is a modern fictional representation of limerence. Another famous historical example was the tumultuous affair between Lord Byron and Lady Caroline Lamb.

A central feature of limerence for Tennov was the fact that her participants really saw the object of their affection's personal flaws, but simply overlooked them or found them attractive. Tennov calls this "crystallization", after a description by the French writer Stendhal. This "crystallized" version of a love object, with accentuated features, is what Tennov calls a "limerent object", or "LO".

Limerence has psychological properties akin to passionate love, but in Tennov's conception, limerence always begins outside of a relationship and before the person experiencing it knows whether it is reciprocated. Tennov observes that limerence is therefore frequently unrequited and argues that some type of situational uncertainty is required for the intense mental preoccupation to occur. Uncertainty could be, for example, barriers to the fulfillment of a relationship such as physical or emotional distance from the LO, or uncertainty about how the LO reciprocates the feeling. Some people may also fear intimacy so that they distance themselves and avoid a real connection.

For Tennov, sexual desire was an essential aspect of limerence; however, the desire for emotional commitment is greater. The sexual desires of Tennov's interviewees were overshadowed by their desire for their beloved to contact them, invite them out and reciprocate their passion. More recent authors have also suggested that sexual desire is a separate (although related) phenomenon and that infatuations such as limerence can sometimes occur in the absence of sexual desire. People are motivated to initiate a pair bond in a way that is different from the sex drive.

Not everyone experiences limerence. Tennov estimates that 50% of women and 35% of men experience limerence based on answers to certain survey questions she administered. Limerence can be difficult to understand for those who have never experienced it, and it is thus often derided and dismissed as undesirable, some kind of pathology, ridiculous fantasy or a construct of romantic fiction. According to Tennov, limerence is not a mental illness, although it can be "highly disruptive and extremely painful", "irrational, silly, embarrassing, and abnormal" or sometimes "the greatest happiness" depending on who is asked.

The original components of limerence, from Love and Limerence, were:

• intrusive thinking about the object of your passionate desire (the limerent object or "LO"), who is a possible sexual partner
• acute longing for reciprocation
• dependency of mood on LO's actions or, more accurately, your interpretation of LO's actions with respect to the probability of reciprocation
• inability to react limerently to more than one person at a time (exceptions occur only when limerence is at low ebb—early on or in the last fading)
• some fleeting and transient relief from unrequited limerent passion through vivid imagination of action by LO that means reciprocation
• fear of rejection and sometimes incapacitating but always unsettling shyness in LO's presence, especially in the beginning and whenever uncertainty strikes
• intensification through adversity (at least, up to a point)
• acute sensitivity to any act or thought or condition that can be interpreted favorably, and an extraordinary ability to devise or invent "reasonable" explanations for why the neutrality that the disinterested observer might see is in fact a sign of hidden passion in the LO
• an aching of the "heart" (a region in the center front of the chest) when uncertainty is strong
• buoyancy (a feeling of walking on air) when reciprocation seems evident
• a general intensity of feeling that leaves other concerns in the background
• a remarkable ability to emphasize what is truly admirable in LO and to avoid dwelling on the negative, even to respond with a compassion for the negative and render it, emotionally if not perceptually, into another positive attribute.

Dorothy Tennov gives several reasons for inventing a term for the state denoted by limerence (usually termed "being in love"). One principle reason is to resolve ambiguities with the word "love" being used both to refer to an act which is chosen, as well as to a state which is endured:

Many writers on love have complained about semantic difficulties. The dictionary lists two dozen different meanings of the word "love". And how does one distinguish between love and affection, liking, fondness, caring, concern, infatuation, attraction, or desire? [...] Acknowledgment of a distinction between love as a verb, as an action taken by the individual, and love as a state is awkward. Never having fallen in love is not at all a matter of not loving, if loving is defined as caring. Furthermore, this state of "being in love" included feelings that do not properly fit with love defined as concern.

(The type of love that focuses on caring for others is called compassionate love or agape.) The other principle reason given is that she encountered people who do not experience the state. The first such person Tennov discovered was a long-time friend, Helen Payne, whose unfamiliarity with the state of limerence emerged during a conversation on an airplane flight together. Tennov writes that "describing the intricacies of romantic attachments" to Helen was "like trying to describe the color red to one blind from birth". Tennov labels such people "nonlimerents" (a person not currently experiencing limerence), but cautions that it seemed to her that there is no nonlimerent personality and that potentially anyone could experience the state of limerence. Tennov says:

I adopted the view that never being in this state was neither more nor less pathological than experiencing it. I wanted to be able to speak about this reliably identifiable condition without giving love's advocates the feeling something precious was being destroyed. Even more important, if using the term "love" denoted the presence of the state, there was the danger that absence of the state would receive negative connotations.

Tennov addresses the issue of whether limerence is love in several other passages. In one passage she clearly says that limerence is love, at least in certain cases:

In fully developed limerence, you feel additionally what is, in other contexts as well, called love—an extreme degree of feeling that you want LO to be safe, cared for, happy, and all those other positive and noble feelings that you might feel for your children, your parents, and your dearest friends. That's probably why limerence is called love in all languages. [...] Surely limerence is love at its highest and most glorious peak.

However, Tennov then switches in tone and tells a fairly negative story of the pain felt by a woman reminiscing over the time she wasted pining for a man she now feels nothing towards, something which occupied her in a time when her father was still alive and her children "were adorable babies who needed their mother's attention." Tennov says this is why we distinguish limerence (this "love") from other loves.

In another passage, Tennov says that while affection and fondness do not demand anything in return, the return of feelings desired in the limerent state means that "Other aspects of your life, including love, are sacrificed in behalf of the all-consuming need." and that "While limerence has been called love, it is not love."

Limerence has been related to passionate love, with Elaine Hatfield considering them synonymous or commenting in 2016 that they are "much the same". Passionate love is described as:

A state of intense longing for union with an other. Reciprocated love (union with the other) is associated with fulfillment and ecstasy. Unrequited love (separation) with emptiness; with anxiety, or despair. A state of profound physiological arousal.

Helen Fisher has considered limerence and passionate love to be synonyms in her papers, but has commented that she prefers the term "romantic love" because she thinks it has meaning in society. Academic literature has never universally adopted a single term for romantic love. Many other authors also consider these terms synonymous, for example Bianca Acevedo & Arthur Aron:

Passionate love, "a state of intense longing for union with another" (Hatfield & Rapson, 1993, p. 5), also referred to as "being in love" (Meyers & Berscheid, 1997), "infatuation" (Fisher, 1998), and "limerence" (Tennov, 1979), includes an obsessive element, characterized by intrusive thinking, uncertainty, and mood swings.

Passionate love is linked to passion, as in intense emotion, for example, joy and fulfillment, but also anguish and agony. Hatfield notes that the original meaning of passion "was agony—as in Christ's passion." Passionate love is contrasted with companionate love, which is "the affection we feel for those with whom our lives are deeply entwined". Companionate love is felt less intensely and often follows after passionate love in a relationship.

In Love and Limerence, Dorothy Tennov also lists passionate love among several synonyms for limerence, and refers to one of Hatfield's early writings on the subject. However, Tennov says that one of the guiding points of her study was to focus on the aspects of love that produced distress. She has also said that one of the problems she encountered in her studies is that her interview subjects would use terms like "passionate love", "romantic love" and "being in love" to refer to mental states other than what she refers to as limerence. For example, some of her nonlimerent interviewees would use the word "obsession", yet not report the intrusive thoughts necessary to limerence, only that "thoughts of the person are frequent and pleasurable".

Various authors have considered "infatuation" to be a synonym for limerence. Dorothy Tennov has stated that she did not use the word "infatuation" because while there is overlap, the word evokes different connotations. In Love and Limerence, Tennov considers "infatuation" to be a pejorative, for example often being used as a label for teenage limerent fantasizing and obsession with a celebrity.

The word "infatuation" is sometimes used colloquially in contrast with "love". In this distinction, according to interviews conducted by Albert Ellis and Robert Harper, people use "love" to refer to relationships which are satisfactory or currently in progress and they use "infatuation" to refer to relationships which turn out to be unsatisfactory in hindsight or which they disapprove of. Elaine Hatfield has suggested that passionate love and infatuation are otherwise indistinguishable at the time one is experiencing them, and that the only difference is semantic.

In the triangular theory of love, by Robert Sternberg, "infatuation" refers to romantic passion without intimacy (or closeness) and without commitment. Sternberg has stated that infatuation in his theory is essentially the same as limerence. Another related concept (which also has qualities reminiscent of limerence) is "fatuous love", which is romantic passion with a commitment made in the absence of intimacy. This can be, for example, lovers in the throes of new passion who commit to marry without really knowing each other well enough to know if they are suitable partners. In this situation, their passion usually wanes over time, turning into a commitment alone (called "empty love") and they become unhappy.

"Infatuation" can also refer to the feelings similar to passionate love, measured by Sandra Langeslag's Infatuation and Attachment Scales (IAS). Infatuation in this context is defined as "the overwhelming, amorous feeling for one individual that is typically most intense during the early stage of love (i.e., when individuals are not (yet) in a relationship with their beloved or are in a new relationship)." Attachment is "the comforting feeling of emotional bonding with another individual that takes some time to develop". The IAS has been used in Langeslag's EEG experiments on love regulation.

Love regulation is "the use of behavioral or cognitive strategies to change the intensity of current feelings of romantic love". A series of experiments have demonstrated that regulating love feelings is possible using a technique called cognitive reappraisal. For example, when love feelings are stronger than desired, one can use a task called negative reappraisal where one focuses on negative qualities of the beloved ("he's lazy", "she's always late"), the relationship ("we fight a lot") or imagined future scenarios ("he'll cheat on me"). Negative reappraisal decreases feelings of infatuation and attachment, but does not switch feelings on or off immediately, so the task must be repeated over time for a lasting change. Negative reappraisal also decreases mood in the short-term, but a distraction task can help ameliorate this. A therapist named Brandy Wyant has had her limerent clients list reasons their LO is not perfect, or reasons they and their LO are not compatible.

Attachment theory refers to John Bowlby's concept of an "attachment system", a system evolved to keep infants in proximity of their caregiver (or "attachment figure"). The person uses the attachment figure as a "secure base" to feel safe exploring the environment, seeks proximity with the attachment figure when threatened, and suffers distress when separated. A prominent theory suggests this system is reused for adult pair bonds, as an exaptation or co-option, whereby a given trait takes on a new purpose.

In Helen Fisher's popular love taxonomy, limerence and attachment are considered different systems with different purposes, with limerence comparable to passionate love and attachment comparable to companionate love. In the past, other authors have also suggested that limerence could be related to the anxious attachment style; however, in their original 1987 paper conceptualizing romantic love as an attachment process (and relating limerence to attachment style), Cindy Hazan and Phillip Shaver also caution that they are not implying that the early phase of romance is equivalent to being attached. They go on to say that "Our idea, which requires further development, is that romantic love is a biological process designed by evolution to facilitate attachment between adult sexual partners who, at the time love evolved, were likely to become parents of an infant who need their reliable care."

Attachment style refers to differences in attachment-related thoughts and behaviors, especially relating to the concept of security vs. insecurity. This can be split into components of anxiety (worrying the partner is available, attentive and responsive) and avoidance (preference not to rely on others or open up emotionally). The formation of attachment style is complicated, for example it has been suggested that attachment style forms during childhood and adolescence, but twin studies have also suggested a heritable component and attachment anxiety is substantially correlated with the personality trait neuroticism. There is also a person-situation problem where people have different attachment styles with different partners, implying attachment style is not just a trait, for example an avoidant partner could cause a secure partner to feel and act anxious.

A 1990 study found that the 15% of participants who self-reported an anxious attachment style scored highly on limerence measures (especially obsessive preoccupation and emotional dependence scales), but found considerable overlap of distributions between all three attachment styles and limerence. Studies and a meta-analysis by Bianca Acevedo & Arthur Aron found that while romantic obsession is associated with relationship satisfaction in short-term relationships, it is associated with slightly decreased satisfaction over the long-term and they speculate this could be related to insecure attachment.

Limerence is sometimes compared to erotomania; however, erotomania is defined as a delusional disorder where the sufferer has a delusional belief that the object of their affection is madly in love with them when they are not. A person suffering from erotomania might interpret subtle, irrelevant details (such as their love object wearing a particular accessory) as coded declarations of love, and the sufferer will invent ways to interpret outright rejections as unserious so they can continue believing the object is secretly in love with them.

According to Dorothy Tennov, a person experiencing limerence might misinterpret signals and falsely believe that their LO reciprocates the feeling when they do not, but they are receptive to negative cues, especially when receiving a clear rejection.

Because limerence is compared to addiction, it is sometimes compared to or contrasted with what is called "love addiction", although according to modern research all romantic love may work like an addiction at the level of the brain. "Love addiction" has had a somewhat amorphous meaning over the years and does not yet denote a psychiatric condition, but recently a definition has been developed that "Individuals addicted to love tend to experience negative moods and affects when away from their partners and have the strong urge and craving to see their partner as a way of coping with stressful situations." This definition is given in terms of a relationship, but limerence is usually unrequited.

Sebastiano Costa et al. have developed an instrument to measure love addiction, based on the six components model of addiction (salience, tolerance, mood modification, relapse, withdrawal, and conflict). The inventory contains items such as urgent feelings to be with the partner, feeling the need to increase meetings, negative mood in the absence of the partner, staying with the partner to relieve negative mood, failing to reduce meetings with the partner and abandoning one's obligations to be with the partner.

In a 1998 essay, as well as in Love and Limerence, Dorothy Tennov has speculated that limerence has an evolutionary purpose.

For what ultimate cause might the state of limerence be a proximate cause? In other words, why were people who became limerent successful, maybe more successful than others, in passing their genes on to succeeding generations back a few hundred thousand or million years ago when heads grew larger and fathers who left mother and child to fend for themselves were less "reproductively successful"—in the long run, that is (Morgan 1993). Did limerence evolve to cement a relationship long enough to get the offspring up and running? [...] The most consistent result of limerence is mating, not merely sexual interaction but also commitment, the establishment of a shared domicile in the form of a cozy nest built for the enjoyment of ecstasy, for reproduction, and for the rearing of children.

Helen Fisher's components of romantic attraction are largely derived from Tennov's components of limerence, and in a similar vein as Tennov, Fisher has theorized that this 'attraction' system evolved to facilitate mammalian mate choice. Tennov has suggested that if the neurophysiological "machinery" for limerence is not a universal among all humans, then having both phenotypes (limerent and nonlimerent) in the population might be beneficial and an evolutionarily stable strategy.

Limerence has been called an addiction. The early stage of romantic love is comparable to a behavioral addiction (i.e. addiction to a non-substance) but the "substance" involved is the loved person. A team led by Helen Fisher used fMRI to find that people who had "just fallen madly in love" showed activation in an area of the brain called the ventral tegmental area, which projects dopamine to other brain areas, while looking at a photograph of their beloved. This as well as activity in other key areas supports the theory that people in love experience what is called incentive salience in response to the loved person, which could be a result of oxytocin activity in motivation pathways in the brain.

Incentive salience is the property by which cues in the environment stand out to a person and become attention-grabbing and attractive, like a "motivational magnet" which pulls a person towards a particular reward. The phenomenon Tennov describes as a loved one taking on a "special meaning" to the person in love is believed to be related to this heightened salience in response to the loved one.

In addiction research, a distinction is also drawn between "wanting" a reward (i.e. incentive salience, tied to mesocorticolimbic dopamine) and "liking" a reward (i.e. pleasure, tied to hedonic hotspots), aspects which are dissociable. People can be addicted to drugs and compulsively seek them out, even when taking the drug no longer results in a high or the addiction is detrimental to one's life. They can also "want" (i.e. feel compelled towards, in the sense of incentive salience) something which they do not cognitively wish for. In a similar way, people who are in love may "want" a loved person even when interactions with them are not pleasurable. For example, they may want to contact an ex-partner after a rejection, even when the experience will only be painful. It is also possible for a person to be "in love" with somebody they do not like, or who treats them poorly. Fisher's team proposes that romantic love is a "positive addiction" (i.e. not harmful) when requited and a "negative addiction" when unrequited or inappropriate.

In brain scans of long-term romantic love (involving subjects who professed to be "madly" in love, but were together with their partner 10 years or more), attraction similar to early-stage romantic love was associated with dopamine reward center activity ("wanting"), but long-term attachment was associated with the globus palludus, a site for opiate receptors identified as a hedonic hotspot ("liking"). Long-term romantic lovers also showed lower levels of obsession compared to those in the early stage.

Limerence is usually unrequited, and a horrible experience for the limerent person. Limerence is debilitating for some people. Lovesickness is a state of mind characterized by addictive cravings, frustration, depression, melancholy and intrusive thinking. In Tennov's survey group, 42% reported being "severely depressed about a love affair". Other effects are distraction and self-isolation. Fisher's fMRI scans of rejected lovers showed activation in brain areas associated with physical pain, craving and assessing one's gains and losses. Tennov describes being under the spell herself, saying "Before it happened, I couldn't have imagined it[.] Now, I wouldn't want to have it happen again." Some people even described to her incidents of self-injury, but Tennov maintains that limerence on its own is normal and tragedies involve additional factors.

Lovesickness has been pathologized in previous centuries, but is not currently in the ICD-10, ICPC or DSM-5. Author and psychologist Frank Tallis has made the argument that all love—even normal love—is largely indistinguishable from mental illness. In his view, the ethical dilemma behind the notion that love could be a psychopathology can be resolved by suggesting that there is no difference between "normal" and "abnormal" when it comes to love. There is also an ethical debate over the implications of using modern drugs for this type of thing. Bioethicist Brian Earp and colleagues have argued that the voluntary use of anti-love biotechnology (for example, a drug made to cause the person who uses it to fall out of love) could be ethical. However, there is currently no drug which is a realistic candidate.

There is a scholarly debate about the involuntary nature of romantic love. The notion that falling in love is an involuntary process is different from the issue of whether one's behavior can be considered autonomous while in love. A series of experiments by Sandra Langeslag have also demonstrated that controlling love feelings is actually possible.

Although limerence was not intended to denote an abnormal state and lovesickness is no longer recognized as a medical condition, symptoms still bear a resemblance to many entries in the DSM. For example, when people fall in love, there are four core symptoms: preoccupation, episodes of melancholy, episodes of rapture and instability of mood. These correspond with conventional diagnoses of obsessionality (or OCD), depression, mania (or hypomania) and manic depression. Other examples are physical symptoms similar to panic attacks (pounding heart, trembling, shortness of breath and lightheadedness), excessive worry about the future which resembles generalized anxiety disorder, appetite disturbance and sensitivity about one's appearance which resembles anorexia nervosa, and the feeling that life has become a dream which resembles derealization and depersonalization.

Tallis argues that love evolved to override rationality so that one finds a lover and reproduces regardless of the personal costs of bearing and raising a child. He uses the example of Charles Darwin who, never being romantic, is said to have sat and made a list of reasons to marry or not to marry. Being accustomed to total freedom and worrying about such things as financial austerities that would limit his expenditure on books, Darwin found his reasons not to marry greatly outweighed his reasons to marry. However, shortly thereafter Darwin unexpectedly fell in love, suddenly becoming preoccupied with cozy images of married life and thus quickly converting from bachelor to husband. Tallis writes:

At first sight, it seems extraordinary that evolutionary forces might conspire to shape something that looks like a mental illness to ensure reproductive success. Yet, there are many reasons why love should have evolved to share with madness several features—the most notable of which is the loss of reason. Like the ancient humoral model of love sickness, evolutionary principles seem to have necessitated a blurring of the distinction between normal and abnormal states. Evolution expects us to love madly, lest we fail to love at all.

According to Tennov, "Love has been called a madness and an affliction at least since the time of the ancient Greeks and probably earlier than that." Historical accounts of lovesickness attribute it, for example, to being struck by an arrow shot by Eros, to a sickness entering through the eyes (similar to the evil eye), to an excess of black bile, or to spells, potions and other magic. Attempts to treat lovesickness have been made throughout history using a variety of plants, natural products, charms and rituals. The first known treatise on lovesickness is Remedia Amoris, by the poet Ovid.

Crystallization, for Tennov, is the "remarkable ability to emphasize what is truly admirable in LO and to avoid dwelling on the negative, even to respond with a compassion for the negative and render it, emotionally if not perceptually, into another positive attribute." Tennov borrows the term from the French writer Stendhal from his 1821 treatise on love, De l'Amour, in which he describes an analogy where a tree branch is tossed into a salt mine. After remaining there for several months, the tree branch (or twig) becomes covered in salt crystals which transform it "into an object of shimmering beauty". In the same way, unattractive characteristics of an LO are given little to no attention so that the LO is seen in the most favorable light. One of Tennov's interviewees, Lenore, says:

Yes I knew he gambled, I knew he sometimes drank too much, and I knew he didn't read a book from one year to the next. I knew and I didn't know. I knew it but I didn't incorporate it into the overall image. I dwelt on his wavy hair, the way he looked at me, the thought of his driving to work in the morning, his charm (that I believed must surely affect everyone he met), the flowers he sent, the considerations he had shown to my sister's children at the picnic last summer, the feeling I had when we were in close physical contact, the way he mixed a martini, his laugh, the hair on the back of his hand. Okay! I know it's crazy, that my list of 'positives' sounds silly, but those are the things I think of, remember, and, yes, want back again!

This kind of "misperception" or "love is blind" bias is more often referred to as "idealization", which modern research considers to be a form of positive illusions. For example, a 1996 study found that "Individuals were happier in their relationships when they idealized their partners and their partners idealized them." However, Tennov argues against the term "idealization", because she says that it implies that the image seen by the person experiencing romantic passion "is molded to fit a preformed, externally derived, or emotionally needed conception". In crystallization, she says, "the actual and existing features of LO merely undergo enhancement." A limerent person may overlook red flags or incompatibilities. Tennov notes that the bias can be an impediment to a limerent person wishing to recover from the condition, as another of her interviewees says:

I decided to make a list in block letters of everything about Elsie that I found unpleasant or annoying. It was a very long list. On the other side of the paper, I listed her good points. It was a short list. But it didn't help at all. The good points seemed so much more important, and the bad things, well, in Elsie they weren't so bad, or they were things I felt I could help her with.

Intrusive thinking is an oft-reported feature of romantic love. Tennov wrote that "Limerence is first and foremost a condition of cognitive obsession." One study found that on average people in love spent 65% of their waking hours thinking about the beloved. Arthur Aron says "It is obsessive-compulsive when you're feeling it. It's the center of your life." At the height of obsessive fantasy, people experiencing limerence may spend 85 to nearly 100% of their days and nights doting on the LO, lose ability to focus on other tasks and become easily distracted.

A limerent person can spend time fantasizing about future events even if they never come true, as the anticipation on its own yields dopamine. According to Tennov, limerent fantasy is unsatisfactory unless rooted in reality, because the fantasizer may want the fantasy to seem realistic enough to be somewhat possible. The fantasies can nevertheless be wildly unrealistic, for example, one person related to her an elaborate rescue fantasy in which he saves an LO's 5-year-old cousin from a group of motorcycles only to be bitten by a snake and die in his LO's lap. This fantasizing along with the replaying of actual memories forms a bridge between one's ordinary life and the eventual hoped for moment of consummation. Tennov says that limerent fantasy is "inescapable", something that just "happens" as opposed to something one "does".

One theory of obsessive thinking draws from the parallel with drug addiction: as the early stage of romantic love is compared to addiction to a person, and drug addicts also exhibit obsessive thinking about drug use. Tennov has written that limerent fantasy based in reality "can be conceived as intricate strategy planning". In the late 1990s, it had also been speculated that being in love may lower serotonin levels in the brain, which could cause the intrusive thoughts. The serotonin hypothesis is based in part on a comparison to obsessive–compulsive disorder, but the experimental evidence is ambiguous. The experiments have tested blood levels of serotonin, with the first experiment finding lowered serotonin levels, but the second experiment finding that men and women were affected differently. This second experiment found that obsessive thinking was actually associated with increased serotonin levels in women.

For some people who have a fear of intimacy or a history of trauma, limerent fantasy might be an escape or a means of having what feels like a relationship but without the threat of real intimacy.

Tennov's conception of fear of rejection was characterized by nervous feelings and shyness around the limerent object, "worried that your own actions may bring about disaster". Awkwardness, stammering, confusion and shyness predominate at the behavioral level. She quotes the poet Sappho who writes "Sweat runs down in rivers, a tremor seizes [...] Lost in the love-trance." One of Tennov's interviewees, a 28-year-old truck driver, said "It was like what you might call stage fright, like going up in front of an audience. [...] I was awkward as hell." Fisher et al. has suggested that fear in the presence of the beloved is caused by elevated levels of dopamine.

Many of the people Tennov interviewed described being normally confident, but suddenly shy when the limerent object is around, or being only in this state of fear with certain limerent objects but not others. Tennov wondered if fear of rejection even serves an evolutionary purpose, by drawing out the courtship process to ensure a greater chance of finding a compatible partner.

According to Tennov, the goal of limerence is "oneness" with the LO, i.e. mutual reciprocation or return of feelings. Limerence subsides in a relationship when the limerent person receives adequate reciprocation from the LO. However, mutual reciprocation is a matter of perception on the part of the limerent person, therefore she says the goal of limerence is "removing uncertainty" about whether or not the LO reciprocates.

Some authors have conceptualized limerence as an attachment process. In the early stages of romantic love, individuals may start out hypervigilant (hyperaware and sensitive to cues) due to uncertainty and novelty, but become synchronized over time as a relationship progresses. Bonding is thought to be in part facilitated by coordinated behaviors which display reciprocity and events which evoke beneficial stress (eustress), like a passionate kiss. Experiments have been done which support the idea that the stress response is involved during the early stage of romantic love, although those measuring cortisol levels have been inconsistent with respect to cortisol being higher or lower.

During the early period of limerence (which may begin as a crush or with a physical attraction), Tennov estimates the limerent person may spend up to 30% of their waking hours thinking about the LO, feel a sense of freedom, elation and buoyancy, and enjoy the preoccupation. Then, when elements of doubt and uncertainty are added to the situation, the time spent preoccupied can soar to even 100% of waking hours, provided there is always some hope the LO might return the feelings. At 100%, this might be joy or despair, depending on whether the limerent person perceives the LO as returning the feelings or rejecting them. One of Tennov's interviewees says "When I felt [Barry] loved me, I was intensely in love and deliriously happy; when he seemed rejecting, I was still intensely in love, only miserable beyond words." Much of the time preoccupied is spent replaying events, searching for their meaning to determine this. These thoughts are felt to be involuntary by the individual, occurring intrusively, even to the point of distraction.

Uncertainty can also be introduced by the presence of barriers to a relationship, or what Tennov calls "intensification through adversity". She writes:

The recognition that some uncertainty must exist has been commented on and complained about by virtually everyone who has undertaken a serious study of the phenomenon of romantic love. Psychologists Ellen Bersheid and Elaine Walster discussed this common observation made, they note, by Socrates, Ovid, the Kama Sutra, and "Dear Abby," that the presentation of a hard-to-get as opposed to an immediately yielding exterior is a help in eliciting passion.

The presence of barriers was crucial to the mutual limerence of Romeo and Juliet, hence this is often called "the Romeo and Juliet effect." Helen Fisher calls this "frustration attraction", and suggests that attraction increases because dopamine levels increase in the brain when an expected reward is delayed. Another theory promoted by Fisher is that separation evokes panic and stress, or activation of the hypothalamic–pituitary–adrenal axis.

Uncertainty can also come in the form of intermittent reinforcements, which prolong the duration of limerence, keeping the brain "hooked" in. Robert Sternberg has written that passionate or infatuated love mainly operates under variable-ratio and variable-interval reinforcement principles, essentially thriving under these conditions:

The available evidence suggests that such love may survive only under conditions of intermittent reinforcement, when uncertainty reduction plays a key role in one's feelings for another (cf. Livingston, 1980). Tennov's (1979) analysis suggests that limerence can survive only under conditions in which full development and consummation of love is withheld and in which titillation of one kind or another continues over time. Once the relationship is allowed to develop or once the relationship becomes an utter impossibility, extinction seems to take place.

Hence, Judson Brewer characterizes the uncertainty of receiving an occasional message from an LO as "gasoline poured on the fire". "Limerence can live a long life sustained by crumbs," says Tennov, who compares this to the uncertainty of gambling: "Both gamblers and limerents find reason to hope in wild dreams."

Similarly, Hatfield has suggested that even being intermittently maltreated can increase passion or spark interest. Consistency generates little emotion, she says, so "What would generate a spark of interest, however, is if our admiring friend suddenly started treating us with contempt—or if our arch enemy started inundating us with kindness." Hatfield recommends that an individual who finds themself attracted to such a person should stay away, as such relationships "leave a residue of ugliness and pain". Intermittent maltreatment is one of the components of trauma bonding.

Tennov writes "It is limerence, not love, that increases when lovers are able to meet only infrequently or when there is anger between them."

However, uncertainty can just be a matter of perception on the part of the limerent person, rather than it being based on actual obstacles or events. One married couple Tennov interviewed was mutually limerent in high school, but each was too shy to make the first move so that each was unaware of the other's attraction. They then met again in college 5 years later and married, but only found out about their mutual limerence in high school through a chance conversation several years after that. Tennov notes that there were no obstacles to their relationship, but suggests their inaccurate perceptions that each was not interested probably increased their limerence in high school.

According to Tennov, because limerence only occurs when there is at least some hope of reciprocation, one can attempt to extinguish limerence by removing any hope that the LO will reciprocate. For example, an individual who is the object of unwanted attraction should give the clearest possible rejection to the limerent person, and not say something such as "I like you as a friend, but..." which is too ambiguous.

The physiological effects of limerence can include trembling, pallor, flushing, weakness, sweating, butterflies in the stomach and a pounding heart. A limerent person has excess energy, with heightened awareness and sustained alertness directed towards the goal of ascertaining reciprocation. Tennov wrote that the sensation of limerence is associated primarily with the heart, even speculating that intrusive thinking results in mutual feedback where thinking of the limerent object causes an increase in heart rate, which in turn changes thought patterns. She says:

When I asked interviewees in the throes of the limerent condition to tell where they felt the sensation of limerence, they pointed unerringly to the midpoint in their chest. So consistently did this occur that it would seem to be another indication that the state described is indeed limerence, not affection (described by some as located "all over", or even in "the arms" when held out in a gesture of embrace) or in sexual feelings (located, appropriately enough, in the genitals).

In Tennov's conception, sexual attraction was an essential component of limerence (as a generalization), although she noted that occasionally people described attractions to her which fit the overall pattern of limerence but did not involve sexual attraction. However, limerence is not the same as sexual attraction, and sex is not the central focus of limerence. When in limerence, "emotional union trumps sexual desire". Tennov stresses that "the most consistent result of limerence is mating, not merely sexual interaction but also commitment" and "the establishment of a shared domicile".

Psychologist Lisa Diamond has written that infatuations like limerence can occur in the absence of sexual desire, citing studies supporting the phenomenon, as well as referencing Helen Fisher's work. Fisher's theory of independent emotions states that there are three primary systems involved with human reproduction and mating: lust (the sex drive), attraction (i.e. passionate love, infatuation or limerence) and attachment (i.e. companionate love), and these work somewhat independently. Diamond argues that people can feel infatuation (in the sense of limerence) without sexual desire, even in contradiction to one's sexual orientation. According to Diamond, there is an evolutionary reason for this, which is that these brain systems are an exaption of mother–infant bonding, meaning the systems were repurposed through evolution. It would not be adaptive for a parent to only be able to bond with an opposite sex child, so the systems must have evolved independent of sexual orientation.

Tennov also drew distinctions between limerent fantasies and sexual fantasies. Limerent fantasies, she says, are grounded in a possible reality, however unlikely, and actually desired to come true. However, sexual fantasies may involve entirely imaginative situations, and may not actually be desired in reality. People also have more voluntary control over their sexual fantasies than their limerent ones, which occur more intrusively.

Shaver and Hazan observed that those suffering from loneliness are more susceptible to limerence, arguing that "if people have a large number of unmet social needs, and are not aware of this, then a sign that someone else might be interested is easily built up in that person's imagination into far more than the friendly social contact that it might have been. By dwelling on the memory of that social contact, the lonely person comes to magnify it into a deep emotional experience, which may be quite different from the reality of the event."

Tennov estimates, based on both questionnaire and interview data, that limerence most commonly lasts between 18 months and three years with an average of two years, but may be as short as mere days or as long as a lifetime. One woman wrote to Tennov about her mother's limerence which lasted 65 years. Tennov calls it the worst case when the limerent person cannot get away, because the LO is a coworker or lives nearby. Limerence can last indefinitely sometimes when it is unrequited, especially when reciprocation is uncertain. This could be such as when receiving mixed signals from an LO, or because of the intermittent reinforcement of an LO ignoring the limerent person for awhile and then suddenly calling.

Tennov's estimate of 18 months to 3 years is sometimes used as the normal duration of romantic love. The other common estimate, 12–18 months, comes from Donatella Marazziti's experiment comparing the serotonin levels of people in love with OCD patients. In this experiment, subjects who had fallen in love within the past 6 months (who were in a relationship) were measured to have serotonin levels which were different from controls, levels which returned to normal after 12–18 months.

According to Tennov, ideally limerence will be replaced by another type of love. In this way, feelings may evolve over the duration of a relationship: "Those whose limerence was replaced by affectional bonding with the same partner might say, 'We were very much in love when we married; today we love each other very much.'" The more stable type of love which is usually the characteristic of long-term relationships is commonly called companionate love, storge or attachment.

In 2008, Albert Wakin, a professor who knew Tennov at the University of Bridgeport but did not assist in her research, and Duyen Vo, a graduate student, suggested that limerence is similar to obsessive–compulsive disorder (OCD) and substance use disorder (SUD). They presented work to an American Association of Behavioral and Social Sciences conference, but suggested that much more research is needed before it could be proposed to the APA that limerence be included in the DSM. They began conducting an unpublished study and reported to USA Today that about 25% or 30% of their participants had experienced a limerent relationship as they defined it.

While limerence and romantic love in general have been compared to OCD since 1998 according to a hypothesis invented by other authors, experimental evidence for a connection with serotonin is ambiguous. This hypothesis was based on a superficial comparison between features of preoccupation shared between the two conditions, for example focusing on trivial details or worrying about the future.

Helen Fisher has commented on Wakin & Vo in 2008, stating that limerence is romantic love and that "They are associating the negative aspects of it with the term, and that can be a disorder." Fisher is one of the original authors to compare limerence to OCD, and has proposed that romantic love is a "natural addiction" which can be either positive or negative depending on the situation. Fisher stated again in 2024 that she does not think there is any difference between limerence and romantic love.

In 2017, Wakin has stated that he feels that brain scans of limerence would help establish it as "something unlike everything that has been diagnosed already", but brain scans have actually been described since as far back as 2002. In Fisher et al.'s original brain scan experiments, all participants spent more than 85% of their waking hours thinking about their loved one. Wakin also claims that a person experiencing limerence can never be satiated, even if their feelings are reciprocated. Tennov found many cases of nonlimerent people who described their limerent partners being "stricken with a kind of insatiability" in this way, and that "no degree of attentiveness was ever sufficient". However, according to Tennov's theory, the intensity of limerence diminishes when the limerent person perceives sustained reciprocation, so it is prolonged inside of a relationship when the LO behaves in a nonlimerent manner. Other authors who are in the mainstream have speculated that unwanted obsession inside a relationship could be related to self-esteem and an insecure attachment style.

In the 1999 preface to her revised edition of Love and Limerence, Dorothy Tennov describes limerence as an aspect of basic human nature and remarks that "Reaction to limerence theory depends partly on acquaintance with the evidence for it and partly on personal experience. People who have not experienced limerence are baffled by descriptions of it and are often resistant to the evidence that it exists. To such outside observers, limerence seems pathological." Tennov states that limerence is normal and says that even those of her interviewees who experienced limerence of a distressing variety were "fully functioning, rational, emotionally stable, normal, nonneurotic, nonpathological members of society" and "could be characterized as responsible and quite sane". She suggests that limerence is too often interpreted as "mental illness" in psychiatry. Tragedies such as violence, she says, involve limerence when it is "augmented and distorted" by other conditions, which she contrasts with "pure limerence".

In a 2005 Q&A, Tennov is asked if limerence can ever lead to a situation such as depicted in the movie Fatal Attraction, but Tennov replies that the movie character seemed to her to be a caricature. Most romantic stalkers are an ex-partner, erotomanic, have a personality disorder, are intellectually limited or socially incompetent.

One writer who investigated the phenomenon of limerence videos on TikTok in 2024 has written that it seemed to her that the many videos created by the relationship coaches there were actually about social media stalking rather than having anything at all to do with limerence.

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