What should I do?
Most Helpful Guy
regardless if you know you are not a threat or not you are to her. Particularly if you don't want to hang out with the ex and him. In her shoes she probably doesn't know you well enough and considering that you are an ex that means that even more than just the random girl you may appear threatening because obviously at sometime her boyfriend found you attractive enough to date.
I think you should try and befriend the new girlfriend. Prove to her that you are not a threat and that your relationship with her boyfriend is strictly platonic. you have to become a non threat in her eyes and the only possible way that will happen is through time, patience and familiarity.