Why do girls do always do this?

I think when other girls see you with a girl they automatically think you are boyfriend material and want you even more. Or it could be something completely different. Tell you what next time you have a girl with you, don't bother noticing other girls, that will give them the idea that you are not interested and you are a one woman's man.

This is a common thing. I am a man and know that girls are almost always interested in a guy when they see he has someone already.

this eminates from the animal kingdom. I will use wolves as an example/ the male wolves are a;ways interested in an alpha male that already has a mate.

competition. before they saw you as a cool person, but now, they can't have you. It's weird I know.

man if theres one thing i learned, women will forever be a mystery