I'm not going to my girlfriends work christmas party because I wanted to play smash bros
Why would you rather play a game instead of go out with your girlfriend?
I really wanted to but my girlfriend didn't want to, she thinks smash bros sucks
You really should be with your partner and not ditch her for video games. It's very rude behavior and childish.
I didn't cheat on her or screw around on her. I'm the one who is being rude here.
Accompanying your girlfiend to an event is the right thing to do. You can always return to your video games at another time, however you may not get an opportunity to attend an event like this with your girlfriend again.