We got in the Alexander discussion and no one could come up with anything but conjecture.
I'd be interested in some chapter, verse, etc. from a book of the era that demonstrates Spartan homosexuality.
Written by Spartans or their enemies?
Relatively books written by Spartans exist. High culture wasn't their forte, generally.
Xenophon, Plato and Aristotle deny it. Others (many of them enemies, or those who would probably be hostile to the Spartans) allege it.