The belief that love is a force beyond our control—that it can be as capricious and devastating as the weather—is so common that it’s built into our language. Love sick. Love struck. We can’t speak about romantic love without using the vocabulary of illness and aggression. Sure, it’s occasionally like a summer’s day, but more often love burns or conquers; it sweeps us off our feet. Lovers collide or are torn apart. Hearts ache and then break. Even smitten comes from smite, a blow from an angry god. And Cupid may be chubby and rosy but he still assaults us with arrows.

“Love is smoke raised with the fume of sighs,” says Romeo, the archetypal Western lover. It is “a madness most discreet/ A choking gall and a preserving sweet.” Whether we are seized, crushed, or captured, falling or afflicted, love happens to us. We are practically powerless, weak-kneed and nauseous, drooling at love’s mercy—or this is what the metaphors we’ve created for love imply.

But before we blame metaphors, it’s worth noting that recent research shows that love causes real pain. Ethan Kross’s fMRI scans showed that the same parts of the brain were activated during social rejection (thinking about a recent break up) and during physical pain. In other words, a broken heart feels a lot like a broken arm. Kross argues that we ought to be a little more sensitive to the pains of those suffering from heartache. (Ahem, college dorm-mates: my “Sarah McLachlan phase” now has scientific backing.)

Intense romantic love has been compared to obsessive compulsive disorder. Lauren Slater describes the research in an excellent essay she wrote on love for National Geographic:

Marazziti compared the lovers’ serotonin levels with those of a group of people suffering from OCD and another group who were free from both passion and mental illness. Levels of serotonin in both the obsessives’ blood and the lovers’ blood were 40 percent lower than those in her normal subjects. Translation: Love and obsessive-compulsive disorder could have a similar chemical profile. Translation: Love and mental illness may be difficult to tell apart. Translation: Don’t be a fool. Stay away.

Not only that, Helen Fisher, a biological anthropologist, suggests that romantic love is, chemically- and practically-speaking, exactly like addiction. And–unfortunately though perhaps not surprisingly–the loss of love, according to fMRI scans, looks a lot like cocaine withdrawal. You can watch her whole TED talk on the subject here. If you’d like a preview, here’s a clip:

Our metaphors are several centuries ahead of our scientists when it comes to love, though this is hardly news to the poets. But I wonder if it’s still possible that our metaphors are setting us up for failure. We hear so much about love, even as children (how old were you the first time you saw Disney’s Cinderella or Sleeping Beauty or another love story marketed specifically to children?), that we have high expectations for it by the time we actually experience it. We expect that love happens to us. And so we are quite passive about love from the start. We expect love to move mountains, to conquer all, to persevere. When it is hard, we are unprepared. When love is inadequate for making a life with someone, we find ourselves adrift and confused. At least, this has been my own experience.

I think this book, if it’s about nothing else, is about the realization that it is not enough to love someone. Why I am shocked to discover—like piano falling from the sky—that love is not enough? The revelation comes again and again and still, it flattens me. Why can’t it be enough to love someone? And why do we insist, despite all evidence to the contrary, on believing that it is?