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  • Why isn't cohabitation before marriage associated with a lower divorce risk? Two big factors: selection and inertia. Tweet This
  • Relationship "inertia": some people may marry a partner they wouldn't have married had they never lived together. Tweet This

The Mystery

For decades, people have believed that living together will increase their odds of doing well in marriage. The core of this idea is that cohabiting would provide a test of a relationship. This seems logical but, mysteriously, decades of research do not show this benefit. In fact, until recently, the overwhelming majority of studies showed that cohabitation before marriage was associated with poorer odds of stability and happiness in marriage.i More recent studies show that the association with higher risk has dissipated or disappeared for some groups.ii And yet the headlines tend to say there is no longer any risk, but that’s misleading in many cases.

Among those who cohabited before marriage, only those who fit the following categories are likely to have marital outcomes similar to those who did not live together before marriage:

  • Only ever cohabited with the person they marry.iii
  • Only began to cohabit after having clear, mutually understood plans to marry their spouse.iv
  • Did not cohabit until the age of 23 or later.v

That leaves the mystery. How could the widely held belief that cohabiting before marriage actually improves one’s odds of marital success have virtually no evidence to support it? (I hedge slightly here because there are a few, rare findings showing this or that group cohabiting and having improved odds.)

There are several explanations for how cohabiting could seem so logical but still not be generally associated with better marriages. I’ll cover the two I think matter most.

First, those who live together before marrying tend to already be at greater risk in marriage because of other factors—for example, having parents who divorced or never married, having fewer economic resources, less education, and so forth. These are called “selection” factors among researchers. Selection suggests that some part of people’s odds for how their relationships or marriages turn out was already baked in their cake, so to speak, before their relationships even began, and an experience like cohabitation may not have altered those odds. There is a lot of evidence that selection is a major factor underlying the mystery I am addressing. The same types of selection factors that are associated with cohabitation and less stable marriages are also associated with greater odds of cohabiting with numerous partners (serially) and cohabiting prior to having clarified plans for a future.

Those who live together before marrying tend to already be at greater risk in marriage because of other factors.

The second explanation is about what people do with their cake after it’s baked. If you like a different metaphor, everyone is dealt a hand of cards, and some people get dealt better hands than others. But no matter what hand they were dealt, it also matters how they play it.


All other things being equal, if two people are sharing one address, they will have a harder time breaking up than a non-cohabiting couple, even if their relationship has serious weaknesses or problems. That is, cohabitation has more inertia than dating. When they move in together, many people increase their constraints for staying in a relationship, or raise the costs of ending it, before they have reached a mutual dedication to being in the relationship.

I found an article a few years ago that nails the way inertia works. In it, Marguerite Reardon describes her commitment dilemma with her iPhone: "Should I break up with my iPhone for Nokia's Lumia 900?" (Her piece is a couple years old, so insert the name for some hot Samsung model into her title.) Here’s a quote from her article.

But sadly now I’m feeling a bit stuck with Apple. I’d like to check out other smartphone platforms, but doing so is going to require some work on my part. Like many who have been sucked into Apple’s clutches, it was innocent in the beginning. . . . Initially, I didn’t realize the commitment I was making. I didn’t think about the fact that I was locking myself into a platform for the rest of my life. But with each new product I bought from Apple, the deeper I fell into the borg. And now I feel like it would be painful to break up with Apple. Not because I love the products or company so much, but because it would be a huge pain in the butt to transfer all my stuff to a new platform.

This is a great definition of what I call iNertia. If you check out her story, she actually goes on to liken the mobile phone dilemma to living together. Most people think readily about inertia related to their mobile plan and being locked in for a year or two. Reardon is addressing a more powerful type of constraint that produces inertia based in the difficulty of moving on because of the depth of what you are already into.

When they move in together, many people increase their constraints for staying in a relationship before they have reached a mutual dedication to doing so.

The idea of inertia as it relates to cohabitation and marriage is a little scary. We believe that some people marry a partner they would not have married if they’d never moved in together. They got “inertialized”—they made it hard to break up—too soon. That’s why my colleague Galena Rhoades and I have predicted and found over and over again that couples who wait to cohabit until marriage or until they have clear, mutual plans to marry report, on average, more marital happiness, less conflict, more compatibility, and so forth.iv  Those couples are less likely to be prematurely caught in inertia.

For some individuals who made it harder to break up before committing to a future with their partner, cohabitation probably decreased their odds of happiness in marriage. Many people who move in together before having clarified anything still do fine in marriage and/or life together. It’s just that they face a greater risk of divorce or unhappiness in marriage than the other group, and it makes sense why that would be the case.

If you are thinking, “well, I don’t really believe in marriage anyway, so what’s this got to do with me?” Inertia is important to understand in any relationship. If you are not already in a committed relationship and you’d like to be, the relevant personal questions are these: What things could I avoid that could make it harder for me to break it off with someone before I’m sure I want to be with that person? How would I know I’m sure?

Inertia is really not all that mysterious once people see it clearly. We all experience it in many ways in modern life. But a lot of people think it’s only an issue when it comes to marriage, not cohabitation. It’s actually everywhere.  When it’s time to really commit to someone, it’s worth accepting that commitment requires making a choice to give up other choices. But too many people give up options before making a real choice.

i. Stanley, S. M., Rhoades, G. K., & Markman, H. J. (2006). Sliding vs. Deciding: Inertia and the premarital cohabitation effect. Family Relations, 55, 499-509.

ii. For example: Manning, W. D., & Cohen, J. A. (2012). Premarital cohabitation and marital dissolution: An examination of recent marriages. Journal of Marriage and Family, 74, 377 - 387.

iii. For example: Teachman, J. D. (2003). Premarital sex, premarital cohabitation, and the risk of subsequent marital dissolution among women. Journal of Marriage and Family, 65(2), 444-455.

iv. For example: Kline, G. H., Stanley, S. M., Markman, H. J., Olmos-Gallo, P. A., St. Peters, M., Whitton, S. W., & Prado, L. (2004). Timing is everything: Pre-engagement cohabitation and increased risk for poor marital outcomes. Journal of Family Psychology, 18, 311-318.; Rhoades, G. K., Stanley, S. M., & Markman, H. J. (2009). The pre-engagement cohabitation effect: A replication and extension of previous findings. Journal of Family Psychology, 23, 107-111.; Stanley, S. M., Rhoades, G. K., Amato, P. R., Markman, H. J., & Johnson, C. A. (2010). The timing of cohabitation and engagement: Impact on first and second marriages. Journal of Marriage and Family, 72, 906-918.

v. Kuperberg, A. (2014). Age at coresidence, premarital cohabitation, and marriage dissolution: 1985-2009. Journal of Marriage & Family, 76(2), 352-369.