XYZ (2000)

Antoine and Marie form, apparently, a couple without history. But, Antoine, obsessed with the image of two young foreigners seen in the restaurant where he works, can no longer make love normally with his partner. And even when the latter, in desperation, agrees to allow herself to be sodomized, it is a complete failure. Ulcerated, Marie kicks Antoine out.
While the latter, trained by a colleague, tries new adventures, each more delirious than the other, with dating girls, Marie confides in her friend Corinne who, soon, makes her discover lesbian pleasures. But Marie doesn't want to stop there and, despite Corinne's warnings, asks a producer to shoot a "test piece" in a porn movie