Id be pretty pissed and grossed out if my kids ever had sex on my bed when they’re older but I wouldn’t kick them out over it, even if they were on a string of shit behavior. I was a teen and had sex on boyfriends parents beds (maybe my parents? I don’t remember but probably). It’s a taboo thing to do, it’s a movie trope for a reason. Kicking someone out for something that’s common for stupid teenagers to do is an extreme over reaction, if she fucks up as much as you say she does I’m sure she’s done something that’s actually been worth kicking out over, this isn’t one of them imo. YTA for sure. Maybe an ESH, but I kind of find it hard fo blame a teenager for doing stupid things sexually, especially taboo things, I know when I was 18 I was more horny than I was logic and I don’t think that necessarily made me an asshole just young and dumb.