Maggie (Greta Gerwig, left) is instrumental in the break up and potential make up of Georgette’s (Julianne Moore) marriage. (John Pack/Sony Pictures Classics)

“Nobody unpacks commodity fetishism like you do.”

Such a statement counts as billing and cooing in “Maggie’s Plan,” a sneakily winning romantic comedy that, despite its ungainliness and sometimes irritatingly broad characters, brings welcome sharpness to a genre usually awash in soft-focus hearts and flowers. A remarriage farce set in the rarefied, jargon-filled world of New York academia (see above), filmmaker Rebecca Miller’s venture into satire takes a comfortable place on a shelf already occupied by Woody Allen, Noah Baumbach and Nicole Holofcener.

Best known for such dramas as “Personal Velocity” and “The Private Lives of Pippa Lee,” Miller doesn’t possess the structural and tonal chops of those directors, or at least not yet. But “Maggie’s Plan” exerts unmistakable charm, and once it hits its stride and the titular scheme kicks into gear, the movie takes on its own weird, giddy rhythms and really soars. Greta Gerwig plays the title character, a bright 30-ish woman who works at the New School for Social Research and has decided she wants to be a mother. After forthrightly deciding to go it alone, Maggie meets John (Ethan Hawke), a “ficto-critical anthropologist” who’s enmeshed in a troubled marriage to Georgette (Julianne Moore), an intellectually imposing author for whom he has subsumed his own writerly ambitions. An affair between needy John and the yielding Maggie is inescapable, as is the breakup and blended families that follow — developments that prompt a case of cold feet in Maggie, who decides to manipulate John and Georgette into getting back together.

It’s the stuff of classic screwball comedy, a genre Miller eagerly embraces, if not with the deft command of the masters. The characters — inspired by an unpublished novel by editor and publisher Karen Rinaldi — come dangerously close to caricatures, especially Moore’s vaguely Teutonic embodiment of post-structuralism at its most humorless and rigid — but the actors infuse them with such spirit and sympathy that “Maggie’s Plan” takes on the glow and infectious warmth of an ensemble piece fired by genuine, spiky affection.

Viewers familiar with Rinaldi’s real-life role in the dissolution of a New York literary marriage in the 1990s (chronicled in Catherine Texier’s scathing roman-a-clef “Breakup”) might look askance at the film’s portrayal of the Other Woman as an unthreatening, almost dowdy Quaker who dresses in calf-length jumpers and thick stockings. (“So pure,” Georgette says of Maggie at one point, “and a little stupid.”) For those in the know, the title character’s guilelessness, and the self-serving revisionism of the plot, are likely to provide a subtext as amusing as the high jinks that ensue with goofy, sometimes brazenly schematic inevitability. (There’s nothing like a convenient snowstorm to help things along.)

But even regarded outside the lens of real-life, the film offers a gently jaundiced, always generous view of so many dynamics that animate love and commitment: the delicate dance between ego and self-sacrifice; how passion gives way to phones and logistics; forgoing self-deception for tough honesty; and finally, how friendship and genuine forms of intimacy can emerge from the messiest circumstances.

Gerwig and Hawke are both superb in their respective roles, bringing their native qualities — Gerwig’s endearing, slightly shambling vulnerability, Hawke’s shrewd understanding of male vanity — to roles they slip into like Maggie’s knit sweaters. As is his recent wont, Bill Hader steals every scene he’s in as Maggie’s supportive-ish ex-boyfriend.

But it’s Moore’s icy, profoundly wounded Georgette who holds “Maggie’s Plan” together — like the rug in “The Big Lebowski,” in which she delivered a performance that rhymes unmistakably with this one. Olympian, intimidatingly stylish, never less than searingly frank, her character manages to wriggle out of the unflattering confines of her initial characterization to become the unlikely savior of the whole enterprise. Together, she and her co-stars create a romantic triangle for the ages — flawed, fractured and often deeply, observantly funny. True to its title, “Maggie’s Plan” is so crazy that it just might work — and it does.

R. At area theaters. Contains obscenity and brief sexuality. 98 minutes.