How can my friend tell her friend to back off her ex?

This is a tough question for me to answer so I need some help. My friend really needs to know if this is right. She and her best friend as close and her best friend lives 28 hours from her because she moved. Well her best friend and and boyfriend broke up. Now my friend has been talking to her best friend's boyfriend everyday on the phone and on AIM. He is starting to like her and her best friend is kinda not talking to her but she said she was over him. But my friend hasn't talked to her best friend in awhile because all her best friend mentions is her ex. And its really annoying to my friend. Also my friends best friends boyfriend calls my friend his future wife.

Should my friend talk to her best friend about this? Or just wait until things get a little more serious. I mean my friend already told her best friend that if it was bugging her to just say something. But my friend does like this guy. And he is nice. So I don't want no one getting hurt so everyone please answer. Help my friend out.

Ok I get what your trying to say. Now this all depends on how close these 2 girls are and why the friend and the boyfriend broke up. You should never let a guy come between friends becos you'll end up losing that friends trust and prob losing her. If your friend values her friendship with her friend she needs to tell her whats been going on, becos it doesnt sound like that friend is over her ex becos she keeps talking about him, so she needs to discuss wats happening and get her opinion on how she feels about her ex and best friend talking so much. Then its up to the friend how much her friend means to her becos you know the rule of you never go after your friends bfs, ex bfs or crushes! just remind her of that.