Gf tells me "You're going to do this with me" without asking if I'm available, or even can. I turn, look at her and say "excuse me?" Because of how rude that statement was, given how busy I am with finals. I then told her its rude to assume I'm free, and instead she can ask again to see if in available since that wouldn't be rude.

So, I done messes up or did I handle this well?