ditto noxy
the only problem i see here is if she is believing what is clearly his lies and getting upset that he hasn't fallen head over heels in love with her.
i used to have a friend who shags everyone who asks - often more than one at a time!
and no matter what i said she still became devastated that they didn't want to start a relationship with her, when she believed that because they wanted to have sex with her must have meant they had feelings for her - she was 34!! you'd think she would have sussed that by now!
she believed she was demonstrating girl power and the sexual liberation of women in the new millenia - and that would have been true and admirable, had she been in control and knew her mind, but she would turn into a wreck - crying, stalking, being abusive etc.
if your friend is happy, let her have some fun, and don;t try to bring her down with accusations of 'innappropriate' behaviour