Science proves love dies (and divorce spikes) after 2 years

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Guest post by Kayt Sukel, author of THIS IS YOUR BRAIN ON SEX: THE SCIENCE BEHIND THE SEARCH FOR LOVE, out this week. Post a comment below to be eligible to win your free copy!

Everyone’s heard of the seven-year-itch—the idea that after seven years together, the shine comes off a relationship and couples “itch” to separate. But neuroscience has found that the itch really hits at the two-year mark – the point at which the biological mojo of the affair fades, and the divorce rates spike.

This shocked me. After all, my own marriage ended after seven years, as did many of my friends’. I always wondered: What is it about this idea of the seven-year-itch (beyond the fun and kitschy Marilyn Monroe film of the same name) that we cling to so?

And does science support the assumption that seven years marks a critical make-or-break point for relationships?

In a word: No.

Statistics show that Americans, on average, actually tend to divorce between the second and third year of marriage—way too soon for our old friend, the seven-year-itch. And what’s fascinating about this, is that recent neurobiological and psychological research keeps demonstrating that two years seems to be a magic number when it comes to love.

For decades, neuroscientists have tried to find some way to characterize passionate love—to figure out what kinds of biological changes explain our extreme changes in focus, attention, mood, energy and general smug annoyingness when we fall fast and hard. Donatella Marazziti, a neuroscientist at the University of Pisa, in Italy, focused her research on hormones. Seems like a sensible place to start, right? After all, if there is anything more pervasive than the idea of the seven-year-itch, it’s that we’re slaves to our hormones. When Marazziti and her colleagues looked at hormone levels in individuals who were passionately in love, they found something striking: heightened levels of testosterone in women and decreased levels of testosterone in men. They also saw increased levels of cortisol, a hormone released in response to stress. Marazziti suggested that these hormone changes represented changes that were happening in the body and the brain to help form a loving bond. But, when Marazziti tested these same individuals two years later, all of the hormones returned to baseline, whether or not they were still in a relationship.

A second study by another group of neuroscientists measured changes in neurotrophins as people fell in love. Neurotrophins are often called “brain fertilizer,” as these proteins help neurons develop, specialize and live longer, promoting learning and memory, much in the same way that fertilizer helps plants to grow. The researchers found that one type of nerve growth factor skyrocketed with the intensity of new love. But once again, levels dropped back to normal after two years.

A new group of psychological studies has also come up with the number two. American and European researchers followed 1700 people for the first 15 years of their marriages. They found that newlyweds initially enjoyed a big boost of happiness. But guess what happens in two years? You guessed it— all that those giddy emotions returned to normal, regardless of relationship status.

Taken together, this “two year” research has led scientists to suggest that it takes about two years to formulate a solid bond between two people. That these changes in brain chemicals (that lead to all those crazy-in-love feelings) are necessary to alter your brain circuitry so you attach to your mate. It makes sense. It wouldn’t be advantageous for it to last forever—I mean, love can pack a hell of a crazy wallop. We’re distracted, soley focused on our lover and can be really irritating. If crazy-love lasted more than those two years, our friends would dump us, our bosses would fire us and the world economy would be on the brink of collapse.

But does this mean that all love relationships are doomed to fail—and only after just two years? Should we just give it all notion of lasting relationships? No, of course not—even now, more than half of American marriages go the distance. In fact neuroimaging studies demonstrate that people who claim to be passionately in love with long-term partners show the same brain signatures as those newly in love—even after decades together. But what this research does show us is that love is a dynamic, changeable thing. Our biology, in concert with our environment, is designed to love, love and love again. We shouldn’t expect every single affair, every single relationship to take the same path and end up in the same place. That’s not the way our biology works works. And not only is that okay, but something that is totally natural.

Kayt and her son.

Kayt and her son.

Kayt Sukel is a wealthy single mommy and the author of THIS IS YOUR BRAIN ON SEX: THE SCIENCE BEHIND THE SEARCH FOR LOVE. While researching her book, she got herself off in an fMRI. When she’s not trying to learn more about the brain in love, Kayt is wondering how so many LEGOs ended up in her bed. It’s just as much of a mystery.

8 thoughts on “Science proves love dies (and divorce spikes) after 2 years

  1. I want one. Awesome post! As a recently re-married and former single mama I am relieved at the conclusion that our bodies adapt and our relationships change and evolve into stronger forms of love.

    Seth and I are just under the two year mark but still very, very much in love. Having three children between the two of us brought us down to reality very quickly. I think that helped make us stronger.

  2. Thought-provoking post… I’m recently divorced and venturing back into the dating scene, so this info is quite timely! I’ve heard that one should give a relationship 18 months before making any long-term decisions (e.g., moving in together, marriage)…seems like the new benchmark should be 2 years!

  3. I wonder, though — you report the divorce rate spikes two years into marriage, but most couples have been together at least several years before the wedding. Relevant?

    1. Definitely relevant.

      It’s interesting–some anthropologists have argued that love lasts as long as it takes to make and raise a baby into childhood.

      But again, for me, what’s interesting about all these numbers is that they show that love doesn’t have to follow one path. That we have the biological capacity to love, love and love again. I like that.

  4. My hub and I lived together for 5 years prior to getting married. During that period we learned a lot about each other. If I were to get married a second time, I’d do the very same thing.

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