I look like Bill Burr bodywise.Honestly, it depends on your stature and value vs. his. I've never had a girl's boyfriend get aggressive with me, they either hate me behind my back or they act overly friendly towards me(sometimes both).
As far as continuing mentally your frame shouldn't change much depending on what a woman says to you. Personally, I think changing your frame to please women is weak beta behavior. When I am in a situation where the girl has a boyfriend I don't change anything. I keep talking about the same stuff. I'm still sexual. I escalate as much as she lets me, and then depending on the girl I will plow through or drop her altogether, same as I would treat any other girl.