Using a fluid naturalism to establish its afterglow vibe, Four Lovers follows two married couples as they swap partners and invigorate their own marriages in the bargain—for a time, at least. Boutique jeweler Rachel (Marina Foïs) is unable to resist tattooed Web designer Vincent (Nicolas Duvauchelle), so she invites him over for dinner; soon her husband, Franck (Roschdy Zem), a writer-photographer behind Eastern-themed erotic coffee-table books, can’t keep his gentle hands off Vincent’s wife, Teri (Élodie Bouchez), a half-American ex–Olympic gymnast. Early on, Rachel cues up Teri’s routine at the 1988 Seoul Games on YouTube—Four Lovers is stronger on the details than on the bigger picture. “Is it normal to feel so good, so quickly?” asks Rachel in retrospective voiceover after they all agree to share each other freely, and the characters begin appearing on-screen in various states of undress. Unsurprisingly, Four Lovers becomes about the precariousness of such arrangements, as jealousy of one form or another strikes each member of the quartet, and the logistical problems mount: The time commitment required by the extramarital activity stretches even the seemingly inexhaustible Teri to her breaking point, and the couples’ children create additional headaches down the line. Co-writer/director Antony Cordier remains sensitive to the subtle shifts in the foursome’s dynamics, but do we really need another handwringer about the perils of polyamory?