I keep looking at and fantasizing about other women despite having a wonderful girlfriend
What other women are you fantasizing about?
Hillary Clinton, Mel Gibson's wife, Doctor Barbra Walters with her perfect face.
It's normal to fantasize about other people. You still think your girlfriend is wonderful which is great. It doesn't mean you will act out on these fantasies.
Actually it is the opposite. I want to act out on my fantasies.
Well, you probably won't get the opportunity so you should just appreciate your girlfriend for now.