Private Passions (1984)

Mark goes to visit his uncle, Albert and his son Toni in Austria for the summer. He develops a serious crush on uncle's pretty stepdaughter Clair and at the same time tries to fend off Toni's efforts to get him set up with prostitutes. As much as he likes Clair, he cannot bring himself to start a sexual relationship with her and ultimately goes to Clair's mother Katherine to vent his feelings. It is that meeting that ultimately sends him home more experienced than when he arrived.