What do you do when your friend keeps talking about a guy that doesn't like her back?

she's been liking this guy for about 4 years and time after time he's said he only sees her as a friend. I think she got the wrong message because he phones her a lot and bought her dinner but he was really just being a nice guy like he is. One day he told her that he can't message her now that he's seeing someone and he caught her despite her knowing he wasn't into her. I'm finding it draining to talk to her becuase she just talks about him and she even spent allt of money visiting his city. She's already 44 and I do feel bad for her because she has never had a husband only just boyfriends that didn't work out.
What do you do when your friend keeps talking about a guy that doesn't like her back?
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