I feel like criticizing my gf's breakfast choices.
Doesn't she always eat a healthy breakfast, with fruit?  What do you find objectionable about that?
What's wrong with fruit? Well it's so unoriginal. She can do so much better!
It's petty to make comments about what someone else chooses to eat, especially when she is making wise choices for her own health.  Even if you find it boring, this is your girlfriend's preference, and she doesn't deserve to be criticized.
I don't care what anyone else thinks. I will make a comment on her food and let out my annoyance.
it is rude to comment on her eating habits if there is no medical reason to. She could be really offended by your statements. You have every right to eat what you want for breakfast and so does she.