I'm not going to change for my girlfriend
Why wouldn't you change for her?
I don't want to make any changes in my life.
You shouldn't change yourself for someone else. If someone is trying to change who you are then you should break up with them.
I don't plan to break up but my girlfriend doesn't like me wearing this shirt.
Well if you really like the shirt then explain to her that you're allowed to wear it. It's not her choice to make.