Why is he interested in me sexually but not romantically?

AnonB17
I have been on and off friends with a guy since I was 15. We are now both approaching 20. I've had a crush on him for as long as I remember. Even now I still kind of do, but unfortunately my feelings were never reciprocated. Now I totally understand that there are guys who find some women dateable and find other women to be not so dateable, and only fuck-able. I'm not dumb. However there's something about the situation that makes it confusing. I am literally a carbon copy of every single girl he has liked and dated in the past, including the girl he likes now. Yet he refuses to consider me as anything other than a friend. He has asked to have sex with me multiple times. All of which I declined. He's obviously physically attracted to me enough to want sex, I have all the qualities of the girls he likes and we have good chemistry and history, so I don't know why he won't give me a chance as more then a friend. I'm exactly like all the girls he's dated, and exactly like the girl he likes now. I'm not a very confident or conceded person but I'd even go as far as to say that I'm better than the girl he likes. But even after all this years I still haven't managed to get him to see me as girlfriend material. So what's the deal?
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+1 y
I'm exactly his type. I have everything he could ever want or need in a girl, yet he continually looks over me. What is it about me that's scaring him off if im exactly what he claims he's looking for in a partner.
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+1 y
He does want a relationship, just with every girl he's like, except for me. And I doubt he's worried about jeopardizing the friendship. It never seemed to be something he cared about before.
Why is he interested in me sexually but not romantically?
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