For years, social scientists have tried to explain why living together before marriage seemed to increase the likelihood of a couple divorcing. Now, new research released by the nonpartisan Council on Contemporary Families gives an answer:
It doesn't. And it probably never has.
This is despite two decades of warnings from academics and social commentators who pointed to studies that claimed a correlation between "shacking up" and splitting up—warnings that increased as the number of couples living together before marriage skyrocketed.
As it turns out, those studies that linked premarital cohabitation and divorce were measuring the wrong variable, says Arielle Kuperburg, a professor at the University of North Carolina, Greensboro, who produced much of the research released Monday. The biggest predictor of divorce, she says, is actually the age at which a couple begins living together, whether before the wedding vows or after.
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"Up until now, we've had this mysterious finding that co-habitation causes divorce," she says. "Nobody's been able to explain it. And now we have—it was that people were measuring it the wrong way."
Couples who begin living together without being married tend to be younger than those who move in after the wedding ceremony – that's why cohabitation seemed to predict divorce, Professor Kuperburg explains. But once researchers control for that age variable, it turns out that premarital cohabitation by itself has little impact on a relationship's longevity. Those who began living together, unmarried or married, before the age of 23 were the most likely to later split.
"Part of it is maturity, part of it is picking the right partner, part of it is that you're really not set up in the world yet," she says. "And age has to do with economics."
Indeed, other research released by the nonpartisan academic group Monday suggests that the longer couples wait to start living together, the better their chances for long-term relationship success.
(Read more: Getting divorced? It pays to get organized first)
This makes sense to historian Stephanie Coontz, director of research and public education at the Council on Contemporary Families.
"Marriages require much more maturity than they once did," she says. In the 1950s, husband and wives stepped into well-defined gender rolls. "Nowadays, people come to marriage with independent aspirations and much greater ideas of equality. Maturity is so important, and negotiating skills are so much more important."