When Love Is Lust (1973)

A decadent countess (Françoise Prévost), middle-aged but still attractive, forces her young and timid daughter (Agostina Belli) to marry a rich butcher. But the couple’s sexual relation is troubled, because the girl has her fair share of inhibitions. So she abandons her house and seeks refuge at her sister’s place. During her absence, her husband finds consolation in his mother in law’s arms.