L\'Ennui - Cedric Kahn (1998)

Middle-aged Martin confused and irritated from the onset of mid-life crisis, has clung too stubbornly to his belief in platonic love and its incumbent celibacy. He inadvertently meets Cecilia who is rumored to have killed her last lover (a painter) with her voracious sexual appetite. Martin, a philosopher, questions everything he experiences; Cecilia, a seemingly indifferent older adolescent, questions nothing at all. Martin's crisis slowly and agonizingly crescendos, in the face of her confounding simplicity, during their brief and bizarre affair.