A friend of mine is thinking of breaking up with her boyfriend. He forgot their one-year anniversary last week. He also kicked her dog and insulted her sister. Utterly mediocre, she calls the relationship. But break-ups are painful. She wonders if she could bear it.

Should she keep him or cut him loose?

The answer is cut, if you take to heart a popular study led by researcher Paul Eastwick and his colleagues at Northwestern and Carnegie Mellon Universities. The psychologists recruited undergrad couples and asked them about the strength of their relationships, how they think they’d deal with a break-up, and for how long they think they’d be upset. Not surprisingly, many lovers thought they’d be crushed.

But the heart is a fickle thing. By the end of the nine-month study, about one-third of the love affairs crashed and burned. And as the lovelorn healed, Eastwick and team evaluated how they coped.

What the psychologists discovered is this: The heart is hardier than you imagine. Newly single men and women were significantly happier than they predicted in the days, weeks, and months after their break-up. This was even true of lovebirds who didn’t think they’d rebound so quickly. Sure, there were tears and pain. But they all recovered quickly and more easily than they thought they would. The people who were most inaccurate at predicting their feelings — and were happily surprised by their own recovery — were those who said they had been very much in love and had not initiated the break-up.

Granted, it’s possible that breaking up is easier for people in their twenties. Healing from multi-year relationships likely takes a lot longer than a few months. But there’s a lesson here for us all, according to the researchers. Facing the prospect of a loss, we overestimate our future distress. Psychologists call this an “impact bias.”

Impact bias research, popularized by Harvard psychologist Daniel Gilbert and his colleagues at Carnegie Mellon and Princeton, has been gaining a lot of traction in the last few years. According to these experts, we’re all terrible at predicting the emotional consequences of things that happen to us. Like fools, we’re too often shocked when it turns out that good things — winning the lottery, buying a dream house, or getting the trophy wife — aren’t as good as we think they’ll be, at least not in the long-term. But bad things — breaking up, getting laid off, or advancing into a recession — aren’t as bad as we think either. After the initial trauma, we snap back to our emotional baselines faster than we think.

Applied to our love lives, the big break-up blowout seems worse than a slow attenuation of affection. But the truth is that we often overestimate the pain of blowouts and underestimate the pain of drawn-outs. That’s why, for some of us, it takes years to break up — even when a relationship is abusive or too tired or troubled to fix. As discussed in BLONDES, the impact bias is a self-protection measure. From an evolutionary perspective, It gives us hope and drive. It helps us value what we have, and can prevent us from being impetuous and destructive. (As a result, we’ll probably take love-preserving drugs in the future.) The downside is that we sometimes stymie and sabotage ourselves out of fear of losing something that has less value than we think. (A plausible argument for fall-out-of-love drugs.)

Tapping into this wisdom, I told my friend that in the long-term she won’t regret leaving a man she doesn’t love enough. Don’t settle for suboptimal. Like removing a band-aid, a break-up may be more painful when done slowly than quickly. And healing, however broken the heart, may happen faster than you think.