AITA for not letting my teen daughter accept a gift from my son's girlfriend?

An old time crush of mine got into a relationship with a guy I knew junior year. Halfway through senior year, I forgot my charger at my classroom and went after class to get it back. As I opened the door, I witnessed the first girl I liked being "mating press" fucked on the teacher's desk by her boyfriend. I quickly shut the door and ran away. Shortly after I saw them leaving school in a hurry. Funny thing is her boyfriend and I ended up going into the same University and major, and he's now one of my closest friends (even after they broke up). Years later, he told me about how one time they were getting it on and "one of the janitors or security, we couldn't see who it was" walked into them, and how they never got freaky on school grounds after that. I'm relieved that they don't know it was me, but God did I almost broke down laughing.

/r/AmItheAsshole Thread