It started the way many household duels do, with a casual remark. She reminded him of a weekend party they'd planned to attend, and he said he wasn't going, he had to work. She wanted to know the real reason, got only vague replies, and finally lost patience: It's you, she said, you have become antisocial.
That blast filled the living room for a beat or two before he confessed that, in fact, he didn't like the party's hostess, never had. He'd gone to her last party, and the one before that, without pouting. He was due for a break. OK?
"He remembers everything and makes mental notes," said Monica Leahy, an apparel buyer in Los Angeles who defused this standoff by calling her husband of eight years, Robert, a name that made them both laugh out loud. "It wasn't a big deal, and I just let it go. You learn to pick your battles, and kind of keep score of what helps and what doesn't."
In defiance of good sense and most love poems, people in long-term relationships do continually (if not always consciously) perform calculations, tallying up the household chores and kid errands, for instance, or estimating the risk of missing the Friday dinner versus the Saturday barbecue. So perhaps it was only a matter of time before the professionals got involved. In a new book, "The Mathematics of Marriage" (MIT Press), a group of mathematicians and a prominent marriage researcher use differential equations to help understand why some apparently fragile marriages endure and why many seemingly loving ones break up. "Instead of merely describing and predicting, we now have a precise language for understanding the dynamics of relationship interactions," said psychologist John Gottman, one of the authors.
Gottman has been studying marital interaction for almost 25 years, by watching how couples interact in his lab at the University of Washington in Seattle. His principal coauthors include James Murray, a former professor of applied mathematics at Oxford University who has studied social interactions; and Rebecca Tyson, a mathematician at Okanagan University College in British Columbia, Canada.
The math itself is not for English majors. Employing the same principles used to describe oscillations around black holes, among other complex systems, the researchers hammer out a series of equally hairy equations. What emerges from the numbers is a familiar relationship dynamic, as changeable as the weather: often remaining balmy (or gloomy) for long periods; subject to gradual warming or cooling spells; and sometimes dashed by a sudden storm.
