This study's findings about low commitment and the gender mismatch in cohabiting adults' expectations suggest three cautionary notes for young adults considering moving in together:

Talk about the future. Both parties--but especially women, given the statistical averages--should be aware that their partner may not be committed to a common future. A long-term cohabiting relationship may prove to be an obstacle, rather than a springboard, to many young people's goal of getting married and starting a family. Shannon's experience suggests that defining the commitment in the relationship (DTCITR) is a matter best addressed before co-signing a lease.

Get on the same page. Couples are more likely to flourish when they share common, clearly communicated goals for their relationship. But given the disparate purposes cohabitation now serves--different people see it variously as a courtship phase, an economical way to save on rent, a venue for convenient sex, a prelude to getting serious, or an alternative to marriage--young adults often end up living with someone who doesn't share their relational goals. Couples considering living together would be wise to talk through the goals they want to accomplish in that move, and make sure they are on the same page.

Don't slide into marriage. Shannon is fortunate in one respect. The only thing worse than being in a relationship for years with an uncommitted person, it would seem, is marrying one. Research by psychologists Scott Stanley and Galena Rhoades, spotlighted in a New York Times op-ed last year, suggests that cohabiting couples are in for trouble when they "slide" into cohabitation and then marriage rather than "decide" to take the same steps. Their work indicates that many couples begin living together without clear expectations, common values, or a shared commitment to one another. And after a time, some of these couples get married, in part because friends, family, and they themselves think it's the logical next step. But without common values and a shared sense of commitment, the couples who slide into cohabitation and marriage, instead of purposely deciding to deepen their commitment to one another, are more likely to divorce.

Stanley and Rhoades illustrate this point by pointing to the research on cohabitation, engagement, and divorce. Women who cohabit prior to engagement are about 40 percent more likely to divorce, compared to those who do not cohabit. By contrast, couples who cohabit after an engagement do not face a higher divorce risk. Those who cohabit only after engagement or marriage also report higher marital quality, not just lower odds of divorce. Stanley and Rhoades think that "sliders" are more likely than "deciders" to cohabit prior to an engagement, and to have trouble in their marriage if they go on to tie the knot. On the other hand, couples who deliberately choose to move in together after a public engagement or wedding are more likely to enjoy the shared commitment that will enable their relationship to last.

So, given the low levels of commitment and the gender mismatch in expectations often found among today's cohabiting couples, young men and especially women who aspire to a strong and stable marriage should take caution when considering moving in together. A live-in relationship that begins brightly, but without the benefit of a serious shared commitment, often ends on a dark note.