Sapho ou La fureur d'aimer (1971)

Françoise Legrand, better known as "Sappho", attractive young woman of the Parisian bourgeoisie, flits from man to man with the consent of Maurice Duran-Vior, his rich protector, a renowned financier. At a social gathering, she meets Lionel de Lancey, younger than she, a cool diplomat, and, as usual, she spends the night with him.