Your Girlfriend seems very identified with being "Chinese". Managing to help her put this identification aside before going into a debate with her would be a good place to start, but is also one of the most difficult things. This is because to have a level headed and enjoyable debate with someone, that can actually go somewhere, there needs to be some leeway of accepting you are totally wrong. I don't see that happening if you can't put your identification aside for a few moments (maybe there is hope, but only you can answer that..).

This is also one of the main reasonst HK has garnered a lot of sympathy from almost every country under the globe, because any clear-headed individual can see how totally unfair the situation is.

Basically, you trying to reason with her would be like banging your head against a brick wall. In my experience, even if you bring out clear-cut, fully reasoned and logical arguments she will pull out every fallacy from under the book before the inevitable of never admitting you're right.