Scum Bag Friend

Mel is a close friend of mine. She is the type of person who never wants to come off impolite, she is very upset if she feels she's made anyone uncomfortable or unhappy. Mel is also very attractive so guys take advantage of her politeness. She may not be interested in a guy but have drinks with him just so his feelings won't be hurt. She's also very trusting and a little naive and has recently been looking to make more friends. This perfect storm led her to start hanging out with a guy who approached her on the subway. She said he wad a cool guy our age and we should all hang out: him, his girlfriend, Mel and I. In passing she mentioned the guy had several times mentioned the size of his profanity to her and half jokingly asked her if shed have a threesome with him and his gf. I thought this was kind of creepy but she assured me he was a nice guy and that he only wanted to be friends. Anyway we all go out together to a bar. After we leave Mel tells me the guy was rubbing up her leg under the table with his gf right there. We decide he wad just drunk but the next time Mel goes out with him and his gf he pulls the same thing. Mel Says she doesn't have enough friends and wants to keep hanging out with this guy. I say he's a creeper and will try to pull somthing.