How to help a friend

How do you tell a friend that she ought not listen to her long distance boyfriend?

Last night we went out with my friend, A., and her boyfriend, P.. While hanging out with R., P. revealed that he doens't think that A. is the woman for his future. They have been dating off and on for 10 years. And A. is planning on moving back to the States for him as she thinks he's going to marry her or at least make her his lifelong partner. Why does she think that? He says things such as 'see...that's why I haven't given you a ring yet' or 'yes, I think it would be interesting to find a job in the UK'. He gives her just enough to make her think he's into her...and she ignores the other things he says that point in a bad direction. He told R. that he doesn't see himself married or having children. Two things A. really wants. And she's convincing herself that she could just live with him, not getting married.

I so don't want her to give up a job she loves in this city she loves for someone who is lying to her. To someone who just doesn't have the balls to just break it off. To someone who wants to cheat on her (confirmed) and most likely already has (not confirmed).

If she was going to move to be closer to her family or because she truly wanted to be back in the States, then I would be all for it. I'd miss her but I'd support this. But not for a guy who won't commit.

What do I say to her? I can't divulge his conversation with R. But I also don't want her to be hurt in the long run and give up her London opportunity. Sigh. Boys suck sometimes.