Come Undone (2000)

Eighteen-year-old Mathieu vacations at the beach with his family when he meets local teen Cédric. After an extremely erotic kiss, the boys begin a passionate romance, complete with skinny-dipping at night, nude dancing on the beach and intense lovemaking in the dunes; yet, as Mathieu grapples with his sexuality and copes with his sick mother, absent father and annoying kid sister, his bond with Cédric grows stronger until it bursts.