I'm annoyed because my girlfriend pees so much
What are you talking about?
She pees on anything she wants like the floor. I have requested her to just pee on the toilet but she won't listen to me.
Everybody has bodily functions so it is not good to be upset about them. You should however talk to them about where they pee so that it doesn't become a toxic environment.
Nah, I think that I am just going to dump her. This isn't a good way to act.
If she has a medical condition you can't blame her. You should be supportive and maybe take her to a doctor if you suspect it may be bladder cancer or kidney failure.