But even great chemistry doesn't always yield a successful relationship. Martina Russo*, 41, was married for five years before she and her husband separated. Though the split was challenging, she was eager to try again, and feels that the lessons she learned from her first marriage have helped her navigate her next relationship successfully. (After four years of being single, Russo remarried last year.) "I am much more respectful of my current husband’s feelings," she says. "With my ex, I was quick to place blame, and was not at all interested in how he got into his various messes. Now, I’m much more respectful. I know that I have to figure out a way to honor my spouse’s desires even if they're different than mine."
Second chances like Russo's aren't uncommon. "We can love more than one person, just the way we can love more than one child or more than one friend," says Pat Love. "The key is knowing that infatuation isn't love. If you’re expecting to stay on that high without having to put forth effort, you’re going to go through that revolving door throughout your life."
But sometimes, divorce may be unavoidable. Over a period of 45 years, Fisher conducted a worldwide study of divorce in 58 societies. "If you’re going to break up, it’s usually around the fourth year of marriage," she says. From an evolutionary perspective, "that's how long a couple had to stay together to raise a child through infancy."