The Principles of Lust (2003)

Paul is a writer with writer's block and increasing problems with listlessness. This changes when he bumps into two people. The first is the charismatic and dangerous risk seeker Billy, who puts him in touch with the darker side of life. And then there is Juliette, a single mother he falls madly in love with. When the initial passion has cooled in their relationship, he has to choose between building up a life with Juliette or following Billy in his quest for the endless high.