In The Marriage-Go-Round, Andrew Cherlin described how Americans’ high marriage rates, high divorce rates, and unstable cohabiting relationships “create a great turbulence in American family life, a family flux, a coming and going of partners on a scale seen nowhere else.” “There are more partners in the personal lives of Americans,” he wrote, “than in the lives of people of any other Western country.”

Cherlin concentrated on marriage and live-in unions, but his observation might extend to less formal romantic relationships as well. Demographer Sharon Sassler, working with coauthors Katherine Michelmore and Jennifer Holland, shows in a new Journal of Marriage and Family article that sexual relationships among young adults in the U.S. are frequently short-lived.

Drawing from the 2006–2010 National Survey of Family Growth, a large and nationally representative survey, Sassler and colleagues restricted their sample to adults ages 18 to 39 who began a sexual relationship with an opposite-sex partner in the 12 months leading up to the survey. The small percentage of respondents who entered a sexual relationship and married in that period without first cohabiting were excluded, and adults in longer-term relationships were excluded by definition. Unsurprisingly, then, the sample tilted young; the mean age was 24.67 years and almost a third of respondents were under age 21.

The goal was to find out what proportion of new sexual relationships had (1) ended in breakup without involving cohabitation, (2) remained intact but non-coresidential, or (3) led to cohabitation (whether ongoing or resulting in marriage or breakup) by the time of the survey. The researchers had to consider the date of first sexual intercourse to be the starting point of a relationship, as the NSFG does not inquire about when the initiation of dating.

The headline discovery: Among young adults who first had sex with their most recent partner 12 months ago, half had since seen the relationship end without cohabiting. Slightly more than a quarter (27%) had begun cohabiting with that partner, and slightly less than a quarter (23%) remained romantically involved without forming a household together.

The figures varied by respondents’ age, race/ethnicity, and family structure in adolescence. As Sassler and colleagues had expected, their more advanced analyses revealed that Americans ages 18 to 20 faced “much higher risks” of relationship dissolution than of cohabiting or continued non-coresidential dating. White young adults were much more apt to begin cohabiting with a new partner than African-Americans. Hispanic young adults showed the least relationship stability: they were more likely than African-Americans to begin cohabiting and to break up with a new partner, and thus the least likely of any group to remain in a stable, non-coresidential relationship.

Family background also predicted how respondents’ latest sexual relationship would progress. Those who lived with a stepparent or no biological parent as teens were roughly 2.5 times as likely to begin cohabiting with a new partner than their peers from married-parent families. Young adults who grew up with a single parent, however, were no more likely to cohabit than them. Adults with college-educated mothers showed a greater likelihood of remaining in a dating relationship, rather than cohabiting, relative to those whose mothers had a high school education or less.

A natural question about studies like this one is: Who cares? Does the progression and dissolution of romantic relationships really matter even when no kids are present? If your eventual goal is a happy, lifelong marriage, then the answer is yes. A German study has found that couples who dated for a longer time prior to cohabiting showed greater long-term stability than faster-moving couples. Beginning to live with a partner soon after forming a relationship “has also been associated with more conflict and lower levels of relationship and sexual satisfaction,” in Sassler, Michelmore, and Holland’s words. Having multiple sexual partners before marriage predicts lower relationship quality and a higher risk of divorce, at least among women, and the link between serial cohabitation and divorce is well-known. Furthermore, some evidence indicates that married couples who became sexually involved early in their dating relationship report lower marriage quality on several different measures. It might sound implausible, but early relationship experiences do seem to carry long-term implications.