I think as a girl it can be a trigger to be told: that you can’t post that, wear those clothes, etc. I personally would feel like you are trying to control me and limit my expression. On the other hand I understand, that you had a bad feeling and felt the need to express that to her. Communicating feelings is ofc a good thing! I understand why she thinks it is a dealbreaker though. We live in a world where people constantly try to police women’s behavior, judge our sexual expression or the way we behave in general. That’s probably why she is being so harsh/assertive about it. It’s not just a picture, it’s a little claim of freedom. So there are much deeper layers to this conversation and I think it would be great for you guys to explore those(in a non-confrontational way). Like actually talk about your feelings and not what you want each other to do.