The Devil in the Heart(1976)

It takes place in a chic milieu, where both the father and the son are in love with the au pair girl (but she sleeps with the dad). The young student is far from the post May 68 clichés and the movie walks a fine line off the beaten path. Philippe Lemaire and Emmanuelle Riva are ideally cast as the bourgeois parents who urge their offspring to attend the grandma's Christmas meal.