I'm looking for the title of a film that I saw back in the 90s. I can't remember anything about the title, but I'm fairly certain the film itself was in French.

The scene that I remember was:
A woman is alone at home during the night, masturbating on her bed. A second woman sneaks into the house (burglar?). She sees the first woman masturbating and is turned on, so she joins her. The following morning, the woman's husband finds the two women naked in bed, and they have a threesome.

I don't have any recollection of any other parts of the movie, but I believe this is the last scene.

Any idea what this movie was called? If not, does anyone know where I can search for adult movies by plot or by keywords?

Thanks!