“My new project will propose that love is not sustainable,” a filmmaker (Dolly Wells, “Doll & Em”) tells an audience in the first trailer for “I Do… Until I Don’t.” “Will you accept that marriage is dead?” she asks. Lake Bell’s follow-up to her directorial debut, “In a World…” seems to be grappling with that very question. Is marriage in fact an outmoded institution?

The comedy follows a trio of couples based in Florida, each at very different points in their relationships. “For Alice and Noah (Bell, Ed Helms), more than a hint of boredom is setting in as they approach their first decade together and the prospect of parenthood,” the film’s official synopsis hints. “Meanwhile, Alice’s funky sister Fanny (Amber Heard) is sure her ‘open marriage’ to Zander (Wyatt Cenac) is the key to their free-spirited happiness. And then there’s Cybil and Harvey (Mary Steenburgen, Paul Reiser), a pair of empty-nesters wondering what the next stage will be.”

The trailer includes revealing footage of the couples’ dynamics and problems, including everything from fertility apps to awkward foreplay to suspected crushes. And as if those issues aren’t enough for the couples to contend with, the documentary filmmaker gets far too actively involved in her job of chronicling their lives. She crosses a serious ethical boundary when she kisses one of her subjects. “I need chaos,” she says.

Bell’s “In a World…” saw the “Wet Hot American Summer: First Day of Camp” star playing a woman working in a sexist, male-dominated industry: voiceover acting. The comedy premiered at the 2013 Sundance Film Festival, where Bell earned the Waldo Salt Screenwriting Award.

“I don’t find it hard to make a film because I am a woman,” Bell has said. “I think if you have a movie to make, make it. If you happen to have a vagina, that’s okay. Still make it.”

“I Do…Until I Don’t” opens September 1. The film was formerly known as “What’s the Point?”