Everyone who studies that sort of thing has told me that viewing ancient roman sexuality through a homosexual vs heterosexual lens is not quite right. You need to look at it more through who's the "passive" vs "active" participant.

That it was socially acceptable to be a man and penetrate someone else regardless of their sex, while it was frowned upon to be a grown man and be penetrated.

Similarly, to receive oral from someone else was fine, but it was frowned upon for a man to perform oral on a woman.

Also my understanding was that it often was a matter of pederasty rather than "love" like when people talk about "marriage equality" nowadays or what not.

Spartans were pretty manly men and homosexual relations were expected of all. It's probably not so much the bed stories as the public behaviors that became associated with it when it was limited mainly to actual homosexuals.