Xavier is both the director of the film and an actor in it who plays the part of "Francis", along with Monia Chokri who play "Marie" and Niels Schneider who plays the part of "Nico." All I can say is that I can relate to what has happened in the film without giving too much of it away.
Xavier says something about growing up gay in this youtube video clip and if you'd like to know more about him, check out this Wikipedia entry for more. I a threesome and the interplay between each person sounds like something to explore, or you just like to know more about the gay experience, buy or rent the dvd! I'm not going to give much of it away. It would spoil the film if I did! - V