Obsession with !!?

My best guy friend, who also happens to be my ex, in my opinion is obsessed with . He recently travelled over seas, and instead of it being a vacation to see the world, he saw it as somewhere he could **** anything that moves. He's only 16, and already he has had with about 11 people. He started when he was 13. I don't know if this is normal at all....But, does he have a problem? I really want to help him, because I do know that he is the relationship kind of guy. I should know I dated him for ages. It just ruins my view of him...Like I don't even want to be around him because I can't even hug him without him getting a hard on. And that isn't even an exaggeration.