First of all, when boys reached a certain age, (I don't remember what it was off the top of my head but it was pretty young) they were sent to live in barracks.
Secondly, it was Thebes, not Sparta who had a group of homosexual warriors, called the sacred band. I have not heard of any other Greek city state with similar ideas.
I am no expert on homosexuality in ancient Greece but someone else on FR pointed out that it was not the same thing as in modern times, in that it did not involve buggery.
I'm sure someone else will come along with more info.