The move toward marriage has not been driven by young gay and lesbian couples rushing to the altar. In both the year before and the year after Obergefell, only one out of seven people whom the Census Bureau classified as in a same-sex marriage was age 30 or younger, according to calculations I’ve done based on the bureau’s American Community Survey. In fact, half of them were age 50 or older. The only way that could have happened, given that same-sex marriage has been legal for less than 15 years, is if large numbers of older same-sex couples who had been together for many years took advantage of the new laws. In other words, changes in state and federal laws seem to have spurred a backlog of committed, medium- to long-term couples to marry.

Why would they choose to do so after living, presumably happily, as cohabiting unmarried partners? In part, they may have married to take advantage of the legal rights and benefits of married couples, such as the ability to submit a joint federal tax return. But the legal issues, important as they are, appear secondary. In a 2013 survey conducted by the Pew Research Center, 84 percent of LGBT individuals said that “love” was a very important reason to marry, and 71 percent said “companionship” was very important, compared to 46 percent who said that “legal rights and benefits” are very important.

Yet the emphasis on love and companionship is not enough to explain the same-sex marriage boom. Without doubt, most of the middle-aged same-sex couples who have married of late already had love and companionship—otherwise they would not have still been together. So why marry now? Marriage became for them a public marker of their successful union, providing them the opportunity to display their love and companionship to family and friends. One reason, of course, was the desire to claim a right so long denied, but that only further underlines the way in which marriage today signals to the wider community the success of a long-standing relationship.

In this sense, these gay couples were falling right in line with the broader American pattern right now: For many people, regardless of sexual orientation, a wedding is no longer the first step into adulthood that it once was, but, often, the last. It is a celebration of all that two people have already done, unlike a traditional wedding, which was a celebration of what a couple would do in the future.

Consistent with this shift in meaning, different-sex couples, like the many of the same-sex couples who have married recently, are starting their marriages later in their lives. According to the Census Bureau, the median age at first marriage—the age at which half of all marriages occur—was 27.4 for women and 29.5 for men in 2017. That’s higher than at any time since the Census began keeping records in 1890. It is six years higher than when I got married in 1972 (at the typical age of 24). In my era, a young couple usually got married first, then moved in together, then started their adult roles as workers or homemakers, and then had children. (I scandalized my parents by living with my future wife before I married her.) Now marriage tends to come after most of these markers are attained.