Maîtresse (1975)
Maîtresse ("mistress" or "teacher", in French), is a 1975 French film directed by Barbet Schroeder, starring Bulle Ogier and, in one of his earliest leading roles, Gérard Depardieu. The film provoked controversy in the United Kingdom and the United States because of its graphic depictions of sado-masochism.
More at Wikipedia.