What should I do?

I have this one friend who SPOILS me. He's always there for me, always reaches out to me, always calls me, spends so much on me (okay but he is rich, so it's not that much to him). He often tells me that he enjoys my company too and flirts with me. He also tells me that he would date me if not for his girlfriend. Despite this - he is very loyal to his girlfriend and has never so much tried to make a move on me romantically. 

Problem is, it's a one-sided friendship and I don't know what to do. We've known each other for 4 years and we're only so close because we lived near each other and took the same bus home every day after high school. He was always just a friend to me but when we went our separate ways to college, he was always reaching out to me and I started to find it a little annoying. I mean, he's a great friend and all, I can't complain - but I just don't have fun around him, and I don't feel like we *get* each other, even though it did to him.

I don't want to be that ******** friend who takes advantage of him, because he's a great friend. I just feel that we don't click and I don't want to be this close to him. But he keeps reaching out and coming over to my place and I can't really say anything. What should I do?

In a different universe, he'd be a great friend. I'm just not getting the same chemistry and feel-good vibes when I'm around him compared to any of my other friends.