Read: The science of cohabitation

After a landmark study from 1992 suggested a link between living together and divorce, a flurry of subsequent studies investigated why this might be. Intuitively, a trial run of living together before marriage should increase the stability of a relationship. One such study questioned whether the relationship between cohabitation and divorce was a product of selection: Could it just be that people who were more likely to consider divorce an option were more likely to live together unmarried?

However, over the years, many researchers began wondering whether earlier findings that linked cohabitation to divorce were a relic of a time when living together before marriage was an unconventional thing to do. Indeed, as cohabitation has become more normalized, it has ceased to be so strongly linked to divorce. Steffen Reinhold, of the University of Mannheim’s Research Institute for the Economics of Aging, pointed out in a 2010 study that in European countries, the correlation disappeared when the cohabitation-before-marriage rate among married adults reached about 50 percent; the U.S. seems to have just gotten to this threshold. In 2012, a study in the Journal of Marriage and Family concluded that “since the mid-1990s, whether men or women cohabited with their spouse prior to marriage is not related to marital stability.” This is the same journal that just published a study finding the opposite.

Galena Rhoades, a psychologist at the University of Denver, has a few theories as to why it’s so difficult to glean what effect, if any, cohabitation has on marital stability. For one, she says, it’s hard to study divorce in ways that are useful and accurate, because the best data sets take so long to collect. Many people don’t get divorced until many years into their marriage, and the social norms around cohabitation in the U.S. have evolved quickly, so “if we study a cohort of people who got married 20 years ago, by the time we have the data on whether they got a divorce or not, their experience in living together and their experience of the social norms around living together are from 20 years ago,” Rhoades told me. In other words, by the time researchers have enough longitudinal data to know whether one is meaningfully linked to the other, the social norms that shaped the findings will hardly be of use to couples today trying to figure out how cohabitation could affect their relationship. Thus, Rhoades said, longitudinal studies tend to paint a full picture of the relationship between living together and divorce, while simultaneously telling Americans today little about the time they actually live in.

Rhoades believes that studies should take into consideration couples’ intentions when they move in together—something neither of the recently published studies does. As she and her colleague Scott Stanley have found in their own research, when analyzing only couples who move in together with the intention of getting married, and thus excluding those who eschew marriage or just want to save money on rent, the heightened risk of divorce disappears. That’s because living together—which often results in a shared apartment lease or ownership of a home, joint custody of pets, or at the very least a shared accumulation of stuff—makes breaking up a greater logistical challenge.