Also has something to do with the absence of acceptable open (or hidden) male/female relationships in Muslim society. You'll notice it happens in prisons as well.
Good point. If you've ever known anyone in the tourism industry who deal with middle eastern countries or westerners who have lived in those places, they will let you in on an open secret. That is that young, good-looking male tourists are advised not to go out alone at night, particularly if they have blond or red hair. What's even more strange is that most of the men there who commit same-sex rapes have wives and children. No doubt that springs from the same thing you mentioned.