Dating a married guy

So I have a friend who is dating a married man and she's really in love with him they've been together for about 8 months now but he still lives with his wife and he just had a baby a few months ago. He tells her that he wants a future with her and everything but they're both in the military and at the same command so they can't be together right now. He says when he transfers he's gonna leave her but I don't think she believes him and I can tell she's hurting that they aren't together. What should I tell her to do?