What happens when hipsters grow up? We’ve seen plenty of movies about hipsters in states of disaffected, post-collegial oblivion, flitting away their days discussing Nietzsche, Kerouac and Kubrick in bohemian coffeehouses. They all but defined the Generation X movement in cinema.

But we’ve seen remarkably little evidence of where those Xers have ended up since the turn of the 20th century. We can only presume that many of them have entered Life, complete with marriages, kids and mundane 9-to-5 jobs.

“Friends With Kids,” which opens on South Florida screens Friday, dramatizes the lives of a few of these people, probably defiant Xers in another life, but who have succumbed to the march of time. A brief prologue shows six friends meeting for dinner in Manhattan. One of them, Leslie (Maya Rudolph) announces that she’s pregnant. Fast-forward four years later, and Leslie and hubby Alex (Chris O’Dowd) have two kids. Their life is a succession of stresses, and their intimacy has suffered, but they’re getting through it. Missy and Ben (Kristen Wiig and Jon Hamm), on the other hand, have also popped out a child, but it seems to have ruined their relationship, a growing catalog of hateful jabs and withering looks. Responsibilities usurp freedom and swallow time, leaving this close-knit sextet more adrift than ever before.

So, in to avoid the traps their friends have fallen into, Jason and Julie (Adam Scott and Jennifer Westfeldt) – lifelong pals but never romantically attached – attempt a grand experiment: They will have, and raise, a child without being involved in a relationship, thus creating a best-of-both-worlds scenario.

Westfeldt, a triple threat who wrote and directed the film, is an astute chronicler of upper-middle class urbanity, refining the intelligent understanding of modern courtship that she displayed 11 years ago on her breakthrough movie, “Kissing Jessica Stein.” Her dialogue has a refreshing authenticity, seesawing convincingly between comedy and tragedy.

This is Westfeldt’s first time directing, and she proves adept at working with actors, even at playing them against type. Wiig has never shown as much dramatic depth as she expresses here in a nearly wordless role as a broken shell of a housewife; it’s a devastating turn. Westfeldt directs herself with charm and vulnerability. Onscreen, she looks half her age and is pretty much the most adorable thing filmed since the latest episode of Animal Planet’s “Too Cute.”

There is a palpable tension in “Friends With Kids” between Westfeldt’s art-house sensibilities and the restrictions of studio-comedy form, which may have something to do with the film’s weaker moments. Naturally, Jason and Julie’s experiment doesn’t go as planned, and naturally, romance blooms unexpectedly, and not always reciprocated. Westfeldt dances awfully close to rom-com clichés before finally succumbing to them, and the character of Jason – a restless playboy afraid to settle down with one woman – is an archetype so tired it should be laid to rest permanently.

But even in its more formulaic passages, there’s an appealing clumsiness to the interactions in “Friends With Kids.” The characters aren’t given the perfect lines to win over their objects of affection – there is no “you complete me” here – so they fumble through it as best they can as they plunge into the future’s uncertainty. It’s what growing up feels like.

“Friends With Kids” opens Friday at most theaters.