The Last Mistress (Une vieille maitresse)

A penniless rogue, Ryno de Marigny, shocks 19th century France with his engagement to the virginal gem of the aristocracy, Hermangarde. As lurid speculations of Ryno's 10-year affair with the carnal Vellini manifest, a supremely erotic and wickedly humorous depiction of human lust is revealed--overriding the brittle facade of nobility and reverence.

Source: Cinema Source