Last night was my school's "All Night Party". They have kids who payed come into the gym from 10 at night til 5 in the morning, so they're safer than going out to drink in the woods or something. Well I went to this party, and so did my SO. I usually really dislike it when she drinks, but I tried hard to be ok with it on this night. That all ended when I saw her grinding with some guy on the dance floor. For anyone who doesn't know what that is, Spoiler (To be fair, it wasn't to this extent. She was not bent down this far.) I got extremely angry and hurt that she would do something like this and called her out on it, and she just said that because her and the guy were friends and that it wasn't going anywhere and that she was just having fun, that it was ok to do it. I asked her not to do it again and she sort of agreed, but then we continued arguing about it. Am I wrong to not want her to do something like this, even if it's not going anywhere? I just don't think that's the way "friends" dance with each other.