Love vs Lust vs Infatuation: How to Tell the Difference

The best-known model comes from the anthropologist Helen Fisher. In a 1998 paper in Human Nature (doi:10.1007/s12110-998-1010-5) she proposed three separate emotion systems for mating. Lust is "the craving for sexual gratification", tied mainly to sex hormones (the estrogens and androgens). Attraction, what most people call being in love, brings energy, focused attention on one person, exhilaration, "intrusive thinking" about them and a craving for emotional union; it is tied mainly to the catecholamines, the family of brain chemicals that includes dopamine. Attachment is the calm, comfortable bond of a long relationship, tied mainly to oxytocin and vasopressin.

The detail that matters most for this question is in a 2002 follow-up (Fisher and colleagues, Archives of Sexual Behavior, doi:10.1023/A:1019888024255). Lust, they wrote, evolved to start mating "with any appropriate partner". Attraction evolved so that people choose and prefer one specific partner. In plain terms, lust isn't very picky about who; infatuation is all about who.

Fisher also argued that in humans the three systems became increasingly independent of each other. That is why you can desire someone you don't love, feel deeply bonded to someone you no longer desire, and lie awake thinking about one person while committed to another.

The psychologist Lisa Diamond came to a similar conclusion from a different direction. In Psychological Review (2003, doi:10.1037/0033-295X.110.1.173) and a shorter 2004 paper (doi:10.1111/j.0963-7214.2004.00287.x) she argued that sexual desire and romantic love are distinct experiences with different evolutionary roots: desire evolved for mating, while love grew out of the bond between infants and the people who care for them. One consequence she discussed is that people sometimes fall in love with someone outside the gender they usually desire. She also noted that women tend to report stronger links between love and desire than men do.

Infatuation is passion without much knowledge of the person. Love includes knowledge: of how they behave when they're tired, scared or wrong. Sternberg described infatuation as love at first sight: it "can arise almost instantaneously and dissipate as quickly under the right circumstances", and comes with racing heartbeat and other bodily arousal.

Some researchers now treat the two as separate dimensions rather than two ends of one line. Sandra Langeslag, Peter Muris and Ingmar Franken (2013, Journal of Sex Research, doi:10.1080/00224499.2012.714011) built a 20-item questionnaire on that idea, with 10 items for infatuation and 10 for attachment. In three samples, the items split cleanly into those two groups. You can have plenty of both, one without the other, or neither.

A test we like: describe the person to a friend. If it's mostly about how they make you feel, it leans toward infatuation; if it's about who they are, irritating parts included, it leans toward love.

Time is the other test. Our view is that infatuation runs on mystery and uncertainty, which real time together uses up. If the feeling is still there once you've seen them at their worst, it has become something more.

Limerence is a word coined by the psychologist Dorothy Tennov in her 1979 book Love and Limerence: The Experience of Being in Love. It describes infatuation at full intensity: constant thoughts about one person, an aching need for them to feel the same, and a mood that rides on every sign of interest or indifference. A 2015 qualitative study described it as an "acute onset, unexpected, obsessive attachment to one person" (Willmott and Bentley, The Qualitative Report, doi:10.46743/2160-3715/2015.1420).

Sternberg considered limerence and infatuation "essentially the same" thing, and added that infatuation, like limerence, "can be quite lasting in duration under certain circumstances". So the length and strength of the feeling don't prove it's love. The difference is where the focus sits. Limerence is about getting the feeling returned; love is about the other person's good. Limerence wants an answer; love can live with one, and usually grows on it.

We should be honest about the research. Limerence is not a diagnosis, and studies of it are few and mostly small. The 2015 study above had six participants, and its authors noted that limerence is rarely reported in the scientific literature. A larger study of unrequited love found little sign of limerent qualities in it, and found unrequited love to be less intense overall than love that is returned (Bringle, Winnick and Rydell, 2013, SAGE Open, doi:10.1177/2158244013492160).

What is better documented is the brain side of intense early love. People who had fallen in love within the previous six months showed changes in a serotonin marker similar to those seen in people with obsessive-compulsive disorder (Marazziti and colleagues, 1999, doi:10.1017/S0033291798007946), and brain scans of people newly and intensely in love showed activity in dopamine-rich reward areas (Aron and colleagues, 2005, doi:10.1152/jn.00838.2004). The obsessive feel of limerence has a physical basis. It doesn't make it an illness. If it is taking over your sleep, work or friendships, though, talking to a counselor or therapist is a sensible step.

There's no exact answer, but there are useful numbers. Tennov put the usual length of the intense phase of being in love at 18 months to 3 years, as summarized in Anna Bode and Geoff Kushnick's 2021 review in Frontiers in Psychology (doi:10.3389/fpsyg.2021.573123). The same review notes that several biological markers measured in people newly in love were no longer different from those of other people 12 to 24 months later.

For love that isn't returned, the study of unrequited love mentioned above reported averages of about 10 months when someone was actively pursuing the other person and about 18 months for someone they knew but had never told, compared with about 21 months for love that was returned (Bringle and colleagues, 2013, as reported by Bode and Kushnick).

In those numbers, the shortest unrequited loves were the ones people acted on and the longest were the ones never spoken. We read that as a hint that a clear answer helps infatuation end and ambiguity keeps it going, though the study wasn't designed to prove it. Getting to know the person well, so that the imagined version gives way to the real one, does the same work from the other side.

An intense phase ending doesn't mean the love does. In a random sample of 274 married Americans, 40% of those married more than 10 years said they were "very intensely in love" (O'Leary and colleagues, 2012, doi:10.1177/1948550611417015). What often fades is the obsessive edge, while the attraction can stay.

Yes, and for many couples that's how it starts. In Sternberg's terms, infatuation is passion alone. Add closeness, the slow work of actually knowing each other, and it becomes romantic love. Add a decision to stay, and it becomes the full kind.

What makes the difference is what happens when the mystery runs out. If finding out who they really are makes you more interested, the infatuation is turning into love. If every new fact is a small disappointment, you were mostly in love with the version you imagined.

The obsessive part doesn't have to survive for the love to be real. A review by Bianca Acevedo and Arthur Aron (2009, Review of General Psychology, doi:10.1037/a0014226) separated romantic love from obsession. Across 25 studies, romantic love without obsession went with higher relationship satisfaction in both short and long relationships, while obsession went with lower satisfaction in long ones. Losing the constant ache is not losing the love.

If you want to keep some of the early spark, there's a simple finding worth knowing: couples who did a new, exciting activity together for just 7 minutes reported better relationship quality afterwards than couples who did something routine (Aron and colleagues, 2000, doi:10.1037/0022-3514.78.2.273).

No single feeling settles it, but five signs together get close.

You miss them actively. This is Sternberg's absence test: when a friend moves away, you miss them and get on with life. When someone you love is away, their absence stays with you and colors your days.

Your attention is fixed on one person. Fisher's attraction system is about one specific partner. If several people would do equally well, it's more likely desire or loneliness than love.

You care how their life goes apart from you. Wanting them to get the job in another city, even though it costs you, is a sign of love. Wanting them only when they're focused on you is a sign of something else.

You know them: not their profile, but their fears, their habits and how they handle a bad day.

You've decided something. Feelings come on their own, but love in the full sense includes a choice, to call it love and to keep showing up.

Our Am I in Love quiz turns these signs into 48 statements about one person you choose, scoring closeness, passion and commitment. It takes about 8 minutes, and the kind of love you feel (infatuation, romantic love, companionate love or one of the other kinds) is free when you finish.

Both happen, and research explains why. If Fisher and Diamond are right that desire and bonding are separate systems, they don't have to switch on together. People describe deep love for a partner with little sexual desire, and strong desire for someone they don't much like.

The systems do overlap, though. A 2012 analysis that pooled brain-imaging studies of sexual desire and of love found they share a striking set of brain areas, with a pattern in one region that seemed to track a progression from desire to love (Cacioppo and colleagues, Journal of Sexual Medicine, doi:10.1111/j.1743-6109.2012.02651.x). Its authors suggested desire and love may sit on a spectrum, with love growing out of desire's pleasant physical experiences. Another study found that brief moments of romantic love and of sexual desire between partners showed up as different feelings and different nonverbal signals, and that the signals of love were related to the release of oxytocin (Gonzaga and colleagues, 2006, Emotion, doi:10.1037/1528-3542.6.2.163).

Desire also changes with time in a relationship, and not the same way for everyone. In a study of 170 university students aged 18 to 25, women's sexual desire was lower the longer their relationship had lasted, while men's was not linked to relationship length (Murray and Milhausen, 2012, doi:10.1080/0092623X.2011.569637). A drop in desire, by itself, doesn't tell you the love is gone.

A quiz can describe how you feel about someone right now. It can't tell you how they feel, whether the relationship will last, or whether you should stay or leave. Feelings shift with a good weekend or a bad month, so an answer today is a snapshot.

That's still useful. Naming what you feel helps you stop arguing with yourself and decide what to do next: slow down, ask a direct question, or give it time.

What we'd avoid is treating any of this as a diagnosis. Lust, infatuation and limerence are normal human experiences, not disorders. If the feelings come with distress that won't lift, or with fears about how someone treats you, talk to a professional or someone you trust rather than a quiz.

If you want to look at the wider pattern in how you love, our attachment style test covers how you handle closeness and distance, and the soulmate test looks at what you believe about finding "the one".