Partenaires (1984)

Most of the action takes place in two dressing rooms of a Parisian theater during the performance of a successful play. Marion, 40, beautiful and famous, is the star. Gabriel, her 55-year-old husband, is less fortunate: he's the one who discovered Marion, but never managed to impose himself. That evening, throughout the performance, the couple will indulge in a savage settling of scores, while the anecdotes of the evening and the other actors provide a comical counterpoint to the monstrous confrontation.

Unfortunately the movie Partenaires is not yet available on HBO Max.