I know how disconcerting this must be. However, I feel like you are looking in the wrong direction. If this is a habit with this person you will never be able to break it or control this. It sounds like self esteem issues. What you can control is who you are friends with. Who are these “girlfriends” that are so easily poachable, to use your word? What kind of friend would not tell you this is happening or think something is wrong with it? I would only surround myself with loyal and loving spirits, not thirsty people with no boundaries. Just something to stew on.