According to a 1999 Rutgers University study, fewer Americans are getting married than at any

time in U.S. history. Researchers attribute this trend to the increasing number of heterosexual couples who live together as a precursor—or as an alternative—to marriage. Currently, more than half of all first marriages are preceded by cohabitation—the term commonly used to describe the status of unmarried sexual partners who share the same household. Many cohabiting couples perceive their

living arrangement as a kind of trial marriage that allows them to see if the relationship will last. “If you’re thinking about spending a really long time with someone, you should know that you’re compatible in all respects,” contends college senior Suzanne Mullane. Cornell University sociologist Marin Clarkberg maintains, furthermore, that cohabitation is an understandably popular...