i would not allow this to happen to me, and i used to think like her too, i thought ex's could be friends even if i was seeing a differrent guy. i learned otherwise because i never met a man that liked it. today i would say i was being selfish, which i was. i wanted to have my cake and eat it too. i hate to admit this about myself, but then i met the right guy and understood what it's all about. its take it or leave it. i say she should stop flirting with this guy because she should see how its hurting you and if she really cares, she'll let go of it.she is the one who has to make a decision. good luck