Last week I wrote about a study that looked at marital quality (essentially a measure of how happy couples were a few years into their marriage) in light of couples’ premarital histories. The report, which tracked 418 young couples in the several years following their marriage, found that certain prenuptial behaviors (like having kids out of wedlock) were associated with lower marital quality.

One association the authors identified was particularly unsettling: “the more sexual partners a woman had had before marriage, the less happy she reported her marriage to be.”  The same was not true for men.

Here’s a chart that one of the report’s authors, Galena K. Rhoades, sent me when I asked for more details.

Source: Galena K. Rhoades, based on data from “Before ‘I Do,’ ” The National Marriage Project. “Higher-quality” marriages represent those in the top 40 percent of the distribution in the sample. Numbers are adjusted for race/ethnicity, years of education, personal income, religiousness (i.e., “All things considered, how religious would you say you are?”), and frequency of attendance at religious services.

The report also found that people who had lived with someone other than a future spouse and/or who had been married previously also reported lower marital quality today.

It might be tempting to interpret the above findings as indicating that “promiscuous” women are doomed to have unhappy marriages. I have serious philosophical issues with that conclusion, but there are methodological problems as well. Correlation does not equal causation, the authors have not randomly assigned spouses in their study to a given number of previous sexual/cohabitating/marital partners, the sample is small, and so on. The authors also control for a few demographic characteristics but not all of them — including age, which (like myriad other variables) could be a major factor in both how many sexual partners a person has before marriage as well as what the marriage itself looks like.

Those are among my serious reservations about assuming a causal relationship. In any case, here is how the authors describe one possible causal explanation for these patterns:

Why would having more experience be associated with worse outcomes? We generally operate under the assumption that people with more experience, in a job, for example, are experts and therefore better than novices or new hires. Shouldn’t having more relationship experience also make people wiser in their love lives?

One reason that more experience could lead to lower marital quality is that more experience may increase one’s awareness of alternative partners. A strong sense of alternatives is believed to make it harder to maintain commitment to, and satisfaction with, what one already has (Rusbult & Buunk, 1993; Thibaut & Kelley, 1959). People who have had many relationships prior to their current one can compare a present partner to their prior partners in many areas — like conflict management, dating style, physical attractiveness, sexual skills, communication ability, and so on. Marriage involves leaving behind other options, which may be harder to do with a lot of experience.

Catherine Rampell is an opinion columnist at The Washington Post.