Is it okay that I want my friend to break up with his girlfriend?
Why do you want your friend to break up?
He is not good for his girlfriend, It will not work
You do not have any say in your friend's relationship. You cannot decide if your friend is good for his gf or not. Just leave them alone.
I think she is much better with me. The guy is a douchebag, she is better off with me.
Even if your friend and his gf break up, you shouldn't then assume you could get her. Stay out of their business.