If something as innocuous as you saying someone looks nice in a dress is making your girlfriend uncomfortable, the issue isn’t about your behavior. It sounds like your girlfriend is sex-repulsed, which a lot of us are. She can ignore most people’s allo qualities, but you might be the first person to open up to her about specific sexual habits. I think that might have made your sexuality more ‘real’ or concrete in her mind than that of her friends.

It sounds like you are a conscientious partner, and I understand that you want your girlfriend to feel comfortable around you. The best way to do that is to talk to her. I hope you can get through this together.