Bridesmaids has led something of a mini-movement toward romantic comedies that reflect romantic realities. Movies in the 27 Dresses mold, with their pastel palettes, clean language and simpery heroines whose main flaw is “caring too much for others,” now seem a bit passé.

Coscripted by its star, Rashida Jones, Celeste & Jesse Forever embodies a new trend of relationship flicks with sharp-tongued heroines who cuss like sailors, drink like fish, screw up their own romantic opportunities and don’t always get happy endings. That sounds promising, but Celeste & Jesse, directed by Lee Toland Krieger, suffers from a wobbly structure and general lack of inspiration. It’s not terrible, but in a crowded field, it isn’t sharp enough to stand out.

The film opens with a solid joke: Celeste and Jesse (Jones and Andy Samberg) are getting divorced after several years of marriage, and they’re better friends than ever. In fact, the duo get along so famously, practically finishing each other’s sentences, that their weirded-out friends, an engaged couple (Ari Graynor and Eric Christian Olsen), ask for time away from them.

Why are these two splitting? The reason is familiar, both from movies and from life: Celeste has drive; Jesse doesn’t. She’s a well-groomed trend spotter for a top LA marketing agency; he dabbles in art and likes to surf. Or, as Celeste puts it, the father of her children should at least have a checking account.

It’s a provocative setup. Traditional wisdom says women always marry up the success ladder, which raises the question of what happens when they don’t. Can an alpha female be happy with a beta male who’s a great partner in every respect but worldly achievement? Plenty of recent comedies, starting with Knocked Up, have explored this conundrum, but always from the perspective of the fun-loving man-child courting the perfectionist ice queen.

Jones has played her share of blandly attractive characters who function as straight women to the funny guys (particularly in I Love You, Man and on “The Office”). When she wrote Celeste & Jesse with Will McCormack (who also appears in the film), she may have wanted to explore the messy reality behind the rigidity. Early scenes establish Celeste as uptight and humorless in public. But the movie gets under her skin as we discover that she needs Jesse, who loosens her up, as much as he needs her, if less openly. Naturally, Celeste realizes this too late — when her ex has already taken her advice and started moving on.

The movie has the loose structure of a semi-improvised comedy, with skit-like scenes of Celeste enduring disastrous dates, or drowning her sorrows in a giant bong, that never quite come together. Sometimes it lurches into a more dramatic mode, with the camera capturing Celeste’s anguish in close-ups. Director Krieger never nails the rhythm that would allow him to make these transitions without jarring the audience. (He had a similar problem with his previous feature, The Vicious Kind, another sort-of-comedy of angst.) When the film wanders into a mishandled subplot about a teen pop star (Emma Roberts) — a frothy detour that would feel more at home in a traditional rom com — it feels like no one’s in the driver’s seat.

If nothing else, Celeste & Jesse establishes Jones as more than a likable second banana to Amy Poehler, the role she’s been playing on “Parks and Recreation.” She holds her own, but her character never evolves much beyond the elementary insight that happiness sometimes means relaxing your standards and not being quite so judgmental. It’s a message familiar from Jane Austen and every rom com she ever inspired, but here it lacks follow-through. Jones and McCormack have bravely chosen not to go for the traditional relationship-movie conclusion, but they haven’t put much of substance in its place. Bittersweet nostalgia forever!