<human>: Can you condense the text into a few key points?

I guess I just would like to talk about how I feel and see if this is normal.

Quick back story, I am 24/m and GF is 22, we have been dating for 2 years 7 months, this is my third long term GF and I am her first. This is my longest relationship and I always do the breaking up. Things just start irritating me more, I start thinking about how I could be happier and I notice that I start to project what my PERFECT girl qualities would be on other women, just women I see on the street or at work and imagine how I would be so much happier with that person, and how I am so unhappy with my current GF which lead me to the eventual break up. I never look back either.

It is happening now with my current GF. She is amazing and like no other girl I dated, she is so smart (3.89 GPA and a Bio major from a good school and will be in med school next year), driven, funny, and BEAUTIFUL!
But lately I have started to get those feelings and we have been fighting more. She is a very, idk how to put it, cold hearted? Not very emotional towards me, constantly takes things out on me during school (we barely talk during finals week for her because she is so stressed) and she has been saying things that make me think she really isn't that nice of a person inside. I am in grad school with a BA in sociology, and many times before she has said rude/condescending remarks about my schooling and career goals (law enforcement after grad school). She gets this behavior from her parents, mainly her mother, just very fake and mean spirited people, but extremely nice on the outside.

I feel guilty thinking like this because I do love her and don't want to leave her, but then another part of me does and I am so torn apart.
<bot>: Getting feelings like I want to move on, but i also want to stay together... curious on why i always get like this in relationships.