I'm going to hang out with friend instead of my girlfriend.
What prompts you to go over to your friend's house rather than your girlfriend's?
My girlfriend doesn't understand me. I think it'd be better to talk with my friend.
I know that you want to talk to your friend, but you must prioritize time for your girlfriend. Not spending time with your gf leads to animosity and eventually a broken relationship.
I'm going to go with my friend.
I can understand your predicament here. You should make time for your girlfriend while also having time for your friend. You should talk to your girlfriend and make special plans with her while also being able to hang out with your friend.