You're right, the Mirror helps. I think it would be better if its status page feature was accessible much earlier, otherwise Exp is just a vague idea.
The clarification from this feature changes my point: Gael gains exp from gay sex but spreads exp with straigth sex? Actually, it's because exp is always granted to the "bottom" while almost all interactions with females have them as the receiving end while males are almost always top.
I think this could be changed rather easily. Cunningulus and blowjobs should both give Mouth exp to the giver. Handjobs and fingering should give exp to the receiver's vagina/penis. Vaginal and anal sex can alternate based on the situation.
I don't mind being top or bottom with men or women. I mind that the game forces you to be bottom with most men while forcing the opposite with women.