In fields of the sciences, romantic love refers to the mental state of being passionately attracted to a specific individual, with focused attention (salience), for the purpose of courtship or pair bonding. The state of romantic love is considered to be a motivation or drive, which is distinct from (but related to) the concept of attachment.

Laypeople may refer to the state as being in love. A variety of other terms are also commonly associated with it. In psychology, it is often referred to as "passionate love". Other terms used to refer to it are "infatuation", "limerence", "obsessive love", and "eros". No single term has been universally adopted by academic literature on the subject.

Research on the biology of romantic love indicates that romantic love resembles addiction during the intense early stage (or when unreciprocated), but academics do not currently agree on how love addictions are defined.

Love which is not reciprocated is called "unrequited love", resulting in lovesickness.

Definition The evolutionary anthropologists Bode and Kushnick undertook a comprehensive review of romantic love from a biological perspective in 2021. They considered the psychology of romantic love, its mechanisms, development across the lifespan, functions, and evolutionary history. Based on the content of that review, they proposed a biological definition:

Researchers draw distinctions between the early stage of romantic love and the "attachment system" theorized by the attachment theorists like John Bowlby. In the past, attachment theorists have argued that attachment theory and attachment styles can replace other theories of love, but academics on love have argued that romantic love and attachment are not identical concepts. The early stage of romantic love is thought to involve additional brain systems for other purposes, with distinct evolutionary histories.

Romantic attraction is also distinct from sexual attraction, although they most often occur together.

Romantic love is not necessarily "dyadic", "social", or "interpersonal", despite being related to pair bonding. Romantic love can be experienced outside the context of a relationship, for example, in the case of unrequited love where the feelings are not reciprocated. A person can develop romantic love feelings before any relationship has occurred, for only a potential partner. The potential partner can even be somebody they do not know well or are not acquainted with at all, as in cases of love at first sight and parasocial attachments.

Variation exists in the way romantic love is expressed in the population. A cross-cultural study of currently in-love people found four clusters, with varying degrees of intensity, obsessive thinking, commitment, frequency of sex, and other differences. Other studies indicate romantic love can be experienced both with or without obsessional features. Typically, intense romantic love is limited to a duration of 12–18 months or as long as 3 years, depending on the estimate; however, in the phenomenon of long-term intense romantic love, some people experience intense attraction inside a relationship, even for 10 years or more. This is similar to early-stage intense romantic love, but with less obsessional features.

Attachment theory

As attachment theory became a prominent framework for explaining adult pair bonds, a contention arose among researchers over how romantic love relates to the "attachment system" from attachment theory. The attachment system was originally conceived of by John Bowlby as a system evolved to keep infants in proximity of their caregiver (or "attachment figure"). The child 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 evolutionary exaptation or co-option, whereby a given trait takes on a new purpose. Adults in romantic or intimate relationships exhibit attachment behaviors with their partners (e.g. proximity seeking, safe haven, separation distress, etc.) which are similar to children with their parents.

In a version of this theory from romantic love researchers, the attachment system became synonymous with companionate love (and therefore distinct from being in love), as in Helen Fisher's popular theory of independent emotion systems.

Initially, it was believed that an attachment bond takes about two years to form, and that such attachment functions play little to no role in new relationships until this occurs. However, later research indicated that the attachment system is in fact active during the early stage of romantic love. A series of studies by Paul Eastwick and Eli Finkel demonstrated that attachment anxiety motivated proximity seeking, with behaviors directed towards relationship formation, even in study participants who were not in a relationship. Furthermore, this "partner-specific" attachment anxiety was distinguishable from the anxious attachment style, and it was associated with an increase in passionate love scores. The attachment system is also believed to be associated with oxytocin, which has been found circulating in people experiencing the early stage of romantic love.

A newer theory then states that romantic love also involves the attachment system, but with additional brain systems for its other features (intense attraction, obsessive thinking, and so on).

Components

The most common measure of romantic love is the Passionate Love Scale, created by Elaine Hatfield and Susan Sprecher. The components of passionate love according to Hatfield & Sprecher are:Hatfield, E. & Sprecher, S. The passionate love scale. In Fisher, T. D., C. M. Davis, W. L. Yaber, & S. L. Davis (Eds.) Handbook of sexuality-related measures: A compendium (3rd Ed.). (pp. 466-468). Thousand Oaks, CA: Taylor & Francis.

Obsessive thinking

Obsessive thinking about a loved one has been called a hallmark or a cardinal trait of romantic love, ensuring that the loved one is not forgotten. Some reports have been made that people can even spend as much as 85 to 100% of their days and nights thinking about a love object. One study found that on average people in love spent 65% of their waking hours thinking about their beloved. Another study used cluster analysis to find several different groups of lovers, with the least intense group spending 35% of their time on average and the most intense at 72%.

Since the late 1990s, these obsessional features have been compared to obsessive–compulsive disorder (OCD). Another theory relates obsessive thinking to addiction, because drug users exhibit obsessive thoughts about drug use as well as compulsions.

Positive illusions

People in love tend to overemphasize the positive aspects of their loved one or relationship, while overlooking or devaluing negative aspects. This is regarded as a type of cognitive bias called positive illusions. The phenomenon has also been referred to as crystallization, idealization, "love is blind" bias, putting the loved one on a pedestal, or seeing through rose-colored glasses.

In the past, some authors have depicted the phenomenon as a malady, arguing that people who idealize would have their partner fall short of their high expectations as a relationship progresses; however, despite this, significant modern scientific evidence has shown that positive illusions actually contribute to relationship satisfaction, long-term well-being and decreased risk for relationship discontinuation.

A study by Marta Kowal and Adam Bode published in 2026 tested the assumption that "love is blind" to a partner's imperfections, in other words, "whether love intensity changes when imperfections become explicit". Half of the participants reflected on their partner's flaws, while the other half (a control group) did not. Love intensity of the participants was then measured using a version of the Triangular Love Scale. Analysis revealed no significant difference in love scores between the two groups of participants—except for those whose partners engaged in aggression or infidelity, who reported lower levels of love. (However this difference could also reflect other preexisting relationship issues.)

Bode & Kowal conclude based on their study that love is not "blind" per se, because lovers can in fact identify the flaws in their beloved; however, "lovers do not necessarily act on these perceptions. Instead, they experience love and maintain their commitment to their partners. Love, in this context, could function as a binding glue that helps sustain the relationship."

Emotional valence

Rather than being a specific emotion itself, romantic love is believed to be a motivation or drive which elicits different emotions depending on the situation: positive feelings when things go well, and negative feelings when awry. Reciprocated love may elicit feelings of joy, ecstasy, or fulfillment, for example, but unrequited love or separation may elicit feelings of sadness, anxiety, or despair.

A 2014 study of Iranian young adults found that the early stage of romantic love was associated with the brighter side of hypomania (elation, mental and physical activity, and positive social interaction) and better sleep quality, but also stronger symptoms of depression and anxiety. Those authors conclude that romantic love is "not entirely a joyful and happy period of life". A different study of adolescents (aged 16 to 21) also found that infatuation in relationships was associated with sleep disturbance too, rather than better sleep quality.

The feeling of romantic love may be either pleasant or unpleasant, regardless of the intensity level. One of Dorothy Tennov's interview participants recalls being in love this way: "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." The intensity of love feelings is also distinct from whether an individual is satisfied with their relationship (although the measures have been shown to be related to some extent). One can be satisfied with their relationship because it fulfills some other need besides love for their partner (like money or child care), or conversely be in love with an abuser in an abusive relationship.

Unrequited love is common among young adults. A study by Roy Baumeister and Sarah Stillwell found that 92.8% of participants reported at least one "powerful or moderate" experience of unrequited love in the past 5 years. A different study found 63% had a "huge crush" at least once in the past 2 years (but not letting the person know), and unrequited love was four times more frequent than equal love. Another found that 20% had experienced unrequited love more than 5 times, according to a definition of "having one’s emotions on a roller coaster, finding it difficult to concentrate, and thinking constantly about the person with whom you are in love. The person is said to have the power to produce extreme highs and lows of emotion in you, depending on how he or she acts towards you."

Obsessive and harmonious passion

The dualistic model of passion (DMP) is a theory invented by the psychologist Robert Vallerand which suggests that passion can be split into two components, termed "obsessive" and "harmonious" passion:

In obsessive passion, a person's passion is driven by internal pressure, controlling them and interfering with other aspects of their life. In harmonious passion, the person experiencing it retains their autonomy, and their passion is more in harmony with other life domains.