L'Amant de Cinq Jours (1961)

Synopsis
American actress Jean Seberg, stars as Claire, a wayward wife, in this routine sex comedy by director Philippe de Broca. Claire's husband is not especially exciting -- he is a button-down civil servant -- and so it is not unusual that she lapse into an affair with Antoine (Jean-Pierre Cassel). There is a serious problem with her choice of a lover, because Antoine happens to be the live-in, "significant other" of Claire's best friend Madeleine (Micheline Presle), a fashion designer. Claire's tangled love life gets worse when Antoine gives every indication he wants to marry her, get a job, and make himself legitimate for once. ~ Eleanor Mannikka, All Movie Guide