An awkward moment occurred at the start of Todd Lappin and Nicole Avril’s wedding rehearsal dinner. The couple’s relatives, many of them traveling to San Francisco from upper-middle-class enclaves in Long Island and New Jersey, arrived early in the evening only to find themselves in a large parking lot connected to an industrial-grade glass-molding warehouse, kilns ablaze. In the lot sat a taco truck the size of an RV and a dozen long folding tables surrounded by Christmas lights. Next to the taco truck was a mobile bar made out of a forklift with plywood in the shape of a shark’s head affixed to the front. The relatives stood in small clusters, a little unglued by the scene. One attendee, the husband of a college friend of the bride’s, stood alone at the entrance, whispering into his cell phone. “Get this, I’m standing in a parking lot…. No, the rehearsal dinner is in the parking lot.”

Lappin, who had planned the evening, was unruffled by the response; it was the one he’d hoped for. The “Night Before,” as he and Avril had called it on the invitation, with its farrago of hard-hat decor, friends-as-entertainment, and neighborhood cuisine, was meant to send a message to relatives in town for the ceremony: You’re not in Jersey anymore. Lappin, 36, grew up in the Garden State, in Hackettstown, on the edge of the Pocono Mountains, and went to college in Rhode Island; Avril, 34, spent her formative years in Setaukut, New York, on the north shore of Long Island. Both wanted to teach their parents something about the life they’d made for themselves on the Left Coast. But to do that, Lappin and Avril needed to shock them out of timeworn expectations. From the looks on the faces of those in attendance that night, it was a mission accomplished.

From the start, Lappin approached the apparatus of marriage celebration determined to do it differently. He and Avril dated for four years before they were engaged, and during that time they attended nearly a dozen nuptials together. Lappin developed an intense dislike for standard-issue ceremonies. “Dinner, dance, cake, dance, go home—it’s so predictable,” Lappin says. “It’s artifice in lieu of authenticity.” Among friends his opinions were widely known. And as they began wagering bets on when Lappin would finally propose, many wondered whether the delay was a holdout against suffering through yet another sleep-inducing matrimonial weekend, this one his own. “Todd had no trouble with the idea of commitment,” Avril says, “but he had an active resistance to the boring, stuffy, overblown aspects of weddings.”

He’s not alone. Many young—and even not so young—couples I’ve spoken with in recent years have faced the decision of when and how to marry with ambivalence. Lappin and Avril are members of a generation that has delayed marriage longer than any other in American history. It is now common for men and women alike to spend 10, 15, even 20 years living single or in a relationship, outside of anything like a conventional family structure.

This protracted prenuptial stage means more than the obvious: that the timing of their lives will be different from their parents’. It also transforms the reasons couples exchanging vows. To marriage delayers like Lappin and Avril, tying the knot doesn’t signal an entry into adulthood, as it did in previous generations, nor does it hinge upon social status or sexual access. Avril, a savvy businesswoman, was not going to say “I do” to Lappin, an editor and writer, with the expectation of being provided for. And marriages no longer have much to do with parents “giving away” their children. If you wait until your thirties to wed, your family probably long ago shuttled you off to a life of your own.

No, the meaning of marriage has entered a kind of free fall. Absent the sturdy support of historical arc or social inevitability, it has become increasingly unmandatory, another in a series of lifestyle options, like buying or renting, taking a full-time job or freelancing. Some couples sign on strictly for the paper, opting for city hall weddings and the pragmatic benefits conferred by legal status. Others bail on the idea entirely, settling into open-ended cohabitations that never want for adjudication.

Couples like Lappin and Avril, though, travel a third route, customizing their ceremonies to give them a spontaneous, performance-art feel—a public proclamation that the whole affair has an entirely different significance for them than it did for their parents. Lappin eventually popped the question after Avril assured him their ceremony needn’t be of the cookie-cutter variety. “The idea,” Lappin says, “was to undercut the solemnity of a wedding while respecting it at the same time.” They gave themselves permission to do something unique—to enhance their wedding ritual by reinventing it.

To better understand their insistence on refashioning the conventional wedding experience, it helps to know a little more about Lappin and Avril. In fact, I’ve known both of them for years. We have long been a part of the same social circle in San Francisco’s Mission District, a stomping ground for hordes of young urban refugees. The gang consists of two dozen tightly knit, strongly integrated friends whose connection to one another has, over time, developed into something more permanent than the sort of transitory and provisional social networks that we knew in high school and college. A loose aggregate in the early ’90s, the core group gradually coalesced into something like a family unit (and, for this reason, served as the inspiration and primary subject matter for my book Urban Tribes: A Generation Redefines Friendship, Family and Commitment, published last year). By the end of the decade, about two dozen of us were spending most of our time together, preparing weekly dinners, attending houseboat trips and dining-car parties, becoming an ever more specific, ever more nuclear part of one another’s lives.