If you want to ruin a dinner party, ask the table whether lust and love are the same thing at different volumes.
Half the guests will tell you yes — that love is just lust that stayed long enough to meet your mother. The other half will be offended on love’s behalf, as though you’d suggested their marriage was a hormone with a mortgage. Someone will use the word “chemistry” without knowing how right they are. Someone else will narrate their entire romantic history and present it as irrefutable evidence. By dessert, two couples are having quiet, separate arguments in the car.
I know this because I have run the experiment. Several times. For science.
Three Types of Love
The love vs. lust debate feels unanswerable in the way all good dinner party questions do. Except this one actually has an answer, and it’s had one for decades.
Her name was Helen Fisher. She was a biological anthropologist, and she spent her career making one argument: that what we call “love” is not one thing. It’s three separate systems, built into the brain at different points in evolutionary history, running on three different chemical budgets, each with its own agenda. Lust. Romantic love. And attachment — companionate love, if you want the textbook name. Three types of love, technically assigned to the same project, coordinating about as well as three government departments.
She built the theory the unglamorous way — decades of research on pair-bonding, from prairie voles upward, tracing which chemicals run which behavior. The famous part came later, when she and her colleagues put people into brain scanners to look at the middle system: people freshly, catastrophically in love, the kind who bring the beloved’s name into conversations about absolutely everything (he’s just so good at parallel parking, you know?). In the scanner, the region that lit up was the reward circuitry — the same machinery that fires in a cocaine addict who has just been shown cocaine.
Not similar machinery. The same machinery.
Lust: The Honest One
Lust is the oldest of the three, and the simplest, because it wants exactly one thing and has never once pretended otherwise. It runs on testosterone and estrogen — equipment we share with every mammal on the planet — and it is millions of years old, and in all that time it has learned nothing, because it has never needed to. It responds to bodies. It holds no view on whether the two of you could survive a rainy Sunday and an IKEA wardrobe together. It does not want to meet your friends. It has no memory, no patience, and no shame, which, frankly, is an enviable way to go through life.
People talk about lust as though it were the deceitful one — the intruder, the thing love must be defended from. Lust has never deceived anyone in its life. It isn’t capable of it. Deception requires a plan.
The one with a plan is next.
Romantic Love: The Con Man
Romantic love — passionate love, in the textbooks — is the drugged phase, and I mean that clinically. Dopamine and norepinephrine surge; you suddenly remember their coffee order, their childhood dog's name, and their exact position on cilantro, yet you do not know what day it is. Sleep becomes optional. Food becomes theoretical. Researchers estimate people in this state spend the vast majority of their waking hours thinking about the beloved, and the remaining hours texting them. A team in Pisa once measured the serotonin of people newly in love and found levels matching patients with obsessive-compulsive disorder. When informed of this, the people in love presumably did not care, because the defining feature of the state is that you cannot be reasoned with.
So — is love an addiction? Fisher’s answer was less metaphorical than you’d hope. When she scanned people who had just been dumped, their reward systems were still firing. Craving, obsession, withdrawal. The full package, minus the person.
Mark Manson calls romantic love a con man, which is as unkind as it is accurate. Its entire job is to take one perfectly ordinary human — a person who says “expresso,” a person who claps when the plane lands — and make them seem like the best person ever to exist. Under its influence, flaws don’t disappear; they get reclassified. He’s not unemployed, he’s between chapters. She’s not rude to waiters, she’s decisive. The con runs for roughly eighteen months to three years. Then the budget runs out, the scaffolding comes down, and you find out what you actually signed.
Companionate Love: The One Nobody Talks About
Companionate love is the third thing, and the one nobody told you about. Oxytocin, vasopressin — the attachment system, the one built for the long haul. It accumulates instead of detonating. It runs on trust and calm instead of anxiety and craving. Nobody writes ballads about it — there is no genre of love song called “you descaled the kettle” — and the movies find it boring, possibly because it’s the only one of the three that is actually about the other person.
The other two, if we’re honest, are mostly about you.
Why You Can Love One Person and Lust After Another
Now the part that all too often isn’t spoken about: the three systems are separable. They are not necessarily stages of one thing. They are three different circuits, and they do not consult each other before firing. You can absolutely feel companionate love for one person and lust for another — in the same afternoon, without any of the three departments filing a conflict-of-interest report. Fisher said this plainly, and it remains the least quoted thing she ever said, for obvious reasons.
It’s why lusting after someone else while in a relationship feels like a scandal and is, neurologically, a Tuesday. Your brain never signed your relationship agreement. Monogamy is something the whole committee has to vote on, repeatedly, and lust always votes no.
Which is not — before anyone gets excited — an excuse. The wiring explains why cheating is possible, it doesn’t say it’s fine (if you’re interested, check out my Cheating is Bad. Probably). The systems fire on their own. What you do about it is the part with your name on it.
Lust vs. Love: The Actual Difference
So: is this lust, or is it love? The problem with the question is that “love” on that ballot is two different candidates running under one name — the drug and the kettle — and they have almost nothing in common. What you’re actually trying to find out is which system has the wheel. And the difference between lust and love, in any version of the question, was never intensity. All three can be intense. The difference is aim. Lust points at a body. Romantic love points at a fantasy currently wearing that body. Companionate love points at the person — the observed, verified person, including all the parts the fantasy quietly edited out.
Think of them as flatmates. Lust wants to know if they’re coming over tonight and whether there are enough condoms in the house. Romantic love has already named and imagined a future for the children — there is a spreadsheet. Companionate love is asking whether anyone has descaled the kettle, because it intends to still be here in March.
Once you have the three-system map, an enormous amount of romantic confusion dissipates. It’s why the first year can feel like the truest thing that’s ever happened to you and still be wrong. It’s why “I love you, but I’m not in love with you” is both a cliché and a chemically precise statement. And it’s why so many people, standing in the ruins of the drugged phase, conclude that love has ended — when what’s ended is the transport, usually at the exact stop where the third system gets on.
Because that’s the real swindle, and it’s the same one I wrote about in Happily Ever After (And Other Recent Inventions): we were sold the middle system as the whole story. The surge, the obsession, the airport chase — that’s where the movies stop, and they stop there for a reason. Romantic love is transient by design. It was never the destination. Yet an entire culture has been taught to judge the journey by how it felt to board.
A friend of mine — fifteen years married, so, a credible witness — was once asked at dinner when she knew her husband was the one. Everyone leaned in, expecting something along the lines of “the moment I saw him”.
She thought about it and said: “About year four.”
Which is either the least romantic thing I’ve ever heard, or the only romantic thing I’ve ever heard. I haven’t decided.
So much truth in so little text. Wish I was there the next time the question is asked at a dinner!