Violette (Julie Delpy) has two grown men vying for her affection and attention in “Lolo”: her new boyfriend, Jean-René (Dany Boon), left, and her 19-year-old son Eloi (Vincent Lacoste). (David Koskas/FilmRise)

French American actress Julie Delpy has become best known in recent years for playing the female half of couples negotiating the complexities of romance, from flings to long-term relationships. In such films as Richard Linklater’s “Before” series and her own directorial projects “2 Days in Paris” and “2 Days in New York,” she imbues her performances with a witty comic sensibility and a refreshing frankness.

“Lolo,” which Delpy wrote, directed and stars in, also focuses on relationship dynamics — one romantic, one parental — but with less comedic and far less successful results.

Delpy plays Violette, a 40-something Paris fashion director who’s been single for years. During a spa vacation in Provence with her best friend Ariane (Karin Viard), she gets together with a divorced IT professional, Jean-René (Dany Boon), who hails from a small coastal town. Although Jean-René is rather nebbishy and provincial, Violette, who’s sick of “smart-ass Parisian guys,” as she puts it, is charmed by his earnestness.

Jean-René soon relocates to Paris, where Violette’s 19-year-old son Eloi (Vincent Lacoste), nicknamed Lolo, has just moved back in with his mother after splitting up with his girlfriend. An emerging artist on the Paris scene, the smug, self-assured Lolo accompanies Violette to in-crowd fashion soirees — Karl Lagerfeld has a brief cameo — and insouciantly struts around the apartment in pastel-colored underwear while his mother spoils and dotes on him.

Seeing Jean-René as competition for his mother’s affections, Lolo devises increasingly high-stakes ploys to torment and humiliate his rival, jeopardizing his mother’s budding relationship. Yet Violette is apparently too lacking in awareness to catch on to her son’s ruses and manipulations, which are occasionally so implausible as to be slightly preposterous.

Little of this comes across as particularly humorous. The frequently raunchy dialogue and numerous jokes about Jean-René’s lack of sophistication may feel a bit too French to work for an American audience. At the same time, Delpy’s portrayal — high-strung, neurotic, prone to mild hysterics — is so reminiscent of some of the actress’s previous roles that it’s hard to forget that you’re watching Delpy, not Violette.

The film also suffers from a frustrating lack of psychological depth. Aside from a few Freudian references that are dropped, unsubtly, in an almost teasing fashion, there’s little in the way of back story to explain Violette and Lolo’s weirdly oedipal bond, not to mention Lolo’s behavior toward Jean-René, which borders on the pathological.

Late in the game, there are more clues as to what’s really been going on. But these revelations are delivered in such a familiar and convenient package that the film’s resolution seems pat. Still, “Lolo” presents a sympathetic take on the ways that midlife romance can push us to reevaluate our relationships, even — maybe especially — the ones we think we know best.

Unrated. At the Angelika Pop-Up at Union Market. Contains sexual situations and crude language. In French with subtitles. 97 minutes.