Lucy Vincent is a neurobiologist with a rich, eclectic career in research, known for her popular science books on the plasticity of the brain and the biology of human attachment. Her newest book, Le cerveau des amoureux (“The Lovers’ Brain“, 2025), is her seventh – yet it returns to the very theme of her first: what, exactly, happens in the brain when we fall in love and how we can keep that feeling alive. Two decades of fresh data on dopamine, oxytocin and other neurotransmitters allow her to revisit the subject with renewed optimism.
Passionate love is a glorious but temporary brain state
The initial rush of dopamine makes partners euphoric, blind to one another’s flaws and convinced the feeling will last forever. Researchers now estimate this phase endures only eighteen to thirty-six months.
When the automatic “high” fades, many people assume they chose the wrong partner and hear themselves say: “I must have been mistaken – I don’t love you after all.” Vincent insists that what has ended is not love but a neurochemical frenzy – a useful “madness” evolution designed to glue two parents to a helpless infant.
According to researchers, love lasts between 18 and 36 months.
Knowing the mechanism prevents unnecessary break-ups
You need to understand what is happening in your brain in order to understand your emotions.
When that passion, those automatic mechanisms, come to an end, most people say:
“Damn, I made a mistake, this isn’t the right person, I chose the wrong one, we need to break up, I don’t love you after all.”
But you have to realize that this delirious passion is just a phase, a kind of madness in the brain. When it stops, it doesn’t mean you don’t love your partner anymore. It means that things are shifting into another mode of functioning. If you understand that, you can see the positive side and find moments together to rekindle that euphoria, to keep it playful and enjoyable.
If you understand that passion is a phase, you can welcome the calmer, deeper mode that follows and deliberately rekindle flashes of early euphoria so that life together stays playful and pleasant.
Oxytocin is the brain’s bonding oil, and sex is its easiest trigger
Sex is a powerful trigger for the release of oxytocin. Even a kiss, or a face-to-face conversation while looking into each other’s eyes, releases it. Oxytocin is the oil that keeps the love brain running. That’s why sex is very important in a couple.
Any intense shared moment releases oxytocin, but sexual intimacy is the most powerful switch. Even a kiss or a long eye-to-eye conversation tops up the supply. Hence, says Vincent, “sex is very important in a couple.”
Desire and attachment live in separate circuits
Sexual desire and romantic attachment are two separate functions in the brain.
Sometimes, you have a partner whose sexual appetite matches yours. When that happens, things tend to go very well. The mechanisms of love and attachment are reignited. But if there’s a strong imbalance between the two partners, it becomes much more complicated. It leads to more conflicts and disagreements than harmony and reconnection. These are things couples need to understand and explore together. You need to carve out intimate moments. Don’t forget to be a couple.
A matched sexual appetite keeps both networks humming and spontaneously restarts attachment. A stark mismatch breeds disputes more often than harmony; partners need to confront this issue together. Nuance aside, her rule of thumb is blunt: “The more you make love, the stronger the couple.”
Intimacy is what separates lovers from friends
When you’re constantly surrounded by family and friends, you forget to be a couple and to create those moments when it’s just the two of you.
That’s when oxytocin is released again – you sort of “enter each other’s brain,” thanks to the mirror neurons, which also play an important role.
These intimate moments help reconsolidate the love circuit.
Long-term love is good for you and for society
Love is fundamental to our lives. We experience it every day, every moment, it’s something within us. We forget how strong what we already have is. Being in a couple brings a lot. People in relationships have better health, stronger immune systems, and are less anxious and less depressed, even if sometimes you have to read a book and work on yourself.
We should advocate for long-term love and everything it brings, on a societal level, and in terms of ageing. Couples who stay together the longest are the ones who live the longest.
People in stable relationships enjoy better health, stronger immune systems and lower rates of anxiety and depression. Couples who stay together the longest also live the longest. Vincent therefore argues for an open advocacy of lifelong love and the benefits it brings to ageing populations.
How to keep the chemistry alive
There’s a lot you can do. Understand your love brain. Work to target each area of the brain involved in the attachment circuit.
For example, the reward circuit is highly sensitive to novelty and surprise: you can create moments to surprise your partner again, to break routine.
In routine, the amount of dopamine released in the reward system gradually decreases, you need to reboost it from time to time.
Another example is the hippocampus, which organizes our memories of the past: reawakening those memories helps bring back the emotional experience of those moments.
One of the functions of love is to ensure that two parents stay close to a highly vulnerable child. Jealousy is useful at that stage to prevent one of them from leaving with someone else.
Her interview (2025, en français)
More of Lucy Vincent
Neural correlates of long-term intense romantic love
Study : Acevedo BP, Aron A, Fisher HE, Brown LL. “Neural correlates of long-term intense romantic love.” Social Cognitive and Affective Neuroscience. Published online 5 January 2011; in print February 2012.
Seventeen people married for over twenty years looked at photos of their spouse while undergoing fMRI scanning. The same dopamine-rich reward areas active in early-stage lovers – ventral tegmental area and striatum – were still strongly engaged. The finding shows that deep, long-lasting love can recruit the very circuits that drive initial passion, contradicting the idea that the chemistry of love must inevitably fade.
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