So, this is an involved topic that often generates (in my view) unnecessary controversy, but I wanted to comment on the framing of the question.

Identifying the 'Ancient Greeks', monolithically conceived, as 'homosexual', a modern concept, is problematic. Probably what you are referring to (correct me if I'm wrong), is the eremenos/erastes relationships that were undoubtedly part of many parts of Archaic and Classical Greece. We certainly have lots of evidence of this from Athens, but not only from there, and these themes crop up in visual arts, myths, and poetry.

I would really object to classifying these relationships as homosexual in the way we understand that term today. These were relationships between mature men and pubescent boys where the men mostly had wives and families of their own and the boys would get married and have children later in life.

Same sex relationships, at least between men of a certain social class, did not exclude heterosexual relationships at all. Mind you, that's true today as well - but what's missing in Ancient Greek Pederasty is the concept of gay vs. straight.

Does that help?