Girlfriend doesn't want to hang with my. what to do?

I'm going out tonight with some friends ( we go to a local college together)to a musical event in L.A tonight(3 girls 2 guys) and I invited my gf to the event 2 weeks ago. One of my good friends cancelled, and he was gonna bring his gf. Now my gf is mad that I'm still going out saying she doesn't wanna be the only couple and she doesn't approve because the girls out number the guys and that it'll just be awkward. ( everyone is in a relationship) Her and I ALWAYS go out and the last time I hung out with my friends was about 2 months ago and we only get to all see one another a few times a year due to busy schedules. So... what do I do? Should I cancel, and do something tonight with just my gf and I, or should I go out? Better yet, what would you do?