Some years ago I started watchin a DVD. Unfortunately I never finished the move, and I don't remember the title. It's probably made around 2000...
The movie is about a young American man who moves to Paris to study. I think it's set around 1968, the year of the student-demonstrations. He meets a French man and woman about his own age (also students?), who invites him to move in with them.
I think the man and woman may be siblings - but they may be just a couple or just house-mates. I also think the two of them are in a sexual relationship (yes, even if they're siblings).
The American man soon gets involved with the woman.
There is especially one scene I remember, where the woman is bathing in a tub, when both men enters the bathroom... or possibly she is bathing with one of the men, when the other enter.