Best Friend is Love Interest

So I'm best friends with the guy I'm falling for, but he's just a a bit of a man whore (absolutely fantastic guy though, seriously). In the case that most of his friends are girls and a lot of them like him and he talks a lot about his 'girl issues' to me quite a bit. I want to be the one he can count on and not make things weird, but if I don't say something he'll for sure ask out this other chick. If I say something I might lose his friendship and it'll be really weird between us, but if I don't, I couldn't be around him for the sake of self-preservation. So either way I pretty much lose, any input?