I'm going to ditch my gf to watch the game
Why do you want to watch the game so badly?
I always treat them as a captive audience and I find it very entertaining
It's understandable that the game is more interesting to you. However, you should not ditch your girlfriend just to watch a game. You should invite her to watch it with you.
You are entitled to not want to watch it, but it is not okay for me to ditch her.
I think that you should just make plans for after the game. That way you still get to watch the game but your partner is not getting their feelings hurt.