The Belt.

Vittorio, an American novelist teaching in Rome, meets the beautiful but damaged Bianca and they rapidly fall into an urgent, tempestuous affair. He's hesitant over their relationship since she seems to thrive on conflict and is constantly baiting him into physical altercation. Bianca gives Vittorio an exquisite leather belt as a gift; he knows immediately that she wants him to whip her with it. Driven by his craving for her, Vittorio complies to Bianca's desire. Their relationship escalates into a dark realm of S&M which becomes more and more self-destructive.