Responses
It’s not cheating... they started dating, but not as a couple; just as people seeing each other to see where it goes, which is why he apologized. Because he was genuinely trying to do that until the actual asshole, blackmailed him about revealing his sexual orientation to people—namely his students and co-workers. Might not seem like a big deal to you, but it is.

You are calling him an asshole why he fucks you, but you are just as bad, or worse cos you are the asshole who is cheating with the one you are calling an asshole, and still what worse too is that it's your first time!! WTF!!