So I was in a situation today that I've never really dealt with before, and I need some opinions/input.

Basically, I was at a party with a girl I recently started seeing. Some random douche starts talking with us for a bit, finishes his drink, and then throws the empty cup onto the girl I'm with. She's like, "what the fuck". The guy was bigger than me and I've never been in a fight before, so I basically just ignored what he did and asked him what he was drinking, basically being a little friendly so he wouldn't try to pick a fight or anything. To be honest, I was a little scared of starting a confrontation with him (he was bigger than me), so my inaction was a result of fear. Do you guys think I fucked up by not acknowledging it and should have called him out on it or confronted him about it? This is something I'd like to take note of, in case something like this happens again in the future.