My friends boyfriend is really hitting on me?

[blondiepink]

I have this friend, and her boyfriend is always hitting on me, Always! I tried to back off from him but he always draws back. I tried telling him in all sorts of ways to back off including that I love my boyfriend and would never hurt him but he dont listen. His messages from facebook are tricky because it starts off with a nice gesture and ends up with him being horny. I want to tell my friend but at the same time something is stopping me. First because she always talks about how she is the luckiest person to have him, she truly loves him and I would feel bad ruining their 4 year relationship over a misleading. Even though he is a big flirt i mean if he flirts with me certainly he flirts with others, because I've seen it I will still feel bad for my friend. The other is because I think he is capable of turning it around to save the relationship and blaming it on me thus losing the relationship with my friend. And I don't want to lose her. Im in a stuck situation and dont know what to do..Help!