Clara and the Why Not (1981)

Three days in the lives of six friends who are nearly 30 years old, live in Grenoble, and have a rock band called the "Why Notes?". They're to play in Paris at Charles's school reunion. In getting to Paris and back, the characters interact with Aimee's ex-husband and her abrasive, cruel ex-mentor, Louise's would-be lover who turns out to have a husband, Mickey's long-time lover and her children, Bertrand's Germanic wife and their children who speak no French, and Frederic's distant mother. The band also meets Clara, a mercurial free spirit who beguiles Bertrand, then Mickey, then takes up with someone else in the band.