His first mistake was "asking her". He should have proceeded with his actions and seduced her and made a physical move on her, built up her attraction for him, showed her he was a man and "swept" her off her feet with an action that she did not think he has balls for (and he doesn't) not a "move' with his mouth (well, not the right kinda move with his mouth anyway lol)..
I've had some success converting friends, but I think this guy went about it the wrong way. By using WORDS, he has already put way too much pressure on this thing.
The way I see this playing out, they'll try to hang out and she will ask him: "do you feel that this is weird", and this is going to scare him BIG TIME, because now she is QUESTIONING their "relationship" (but in reality, there is no relationship, just a world of pressure because of his obsession with her and the implied relatioship or dating because of him running his mouth and asking to "date her") so now when he starts getting some red flags and mixed feelings, he will FREAK OUT, because this is THE ONLY GIRL FOR HIM ever, so he is putting soooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo much importance on this girl on putting her on such a high pedestal that she can NEVER live up to it. Even if she is a GREAT girl, she is not a HEAVENLY ANGEL that he thinks she is, and deep down, even subconsiously, she knows this... If he doesnt' start treating her "normal", he will loose her quickly,, he will scare her off, her interest level is probably not even there..
the only reason I think she is accepting is because she actually REALLY wants to be attracted to him!!! She REALLY does!! but she's not! She knows that he is a really nice guy, would treat her really well, would probably make a GREAT husband, but she just DOESN'T feel anything for him!! And it's not her fault, I mean, one doestn't choose how they feel, she simply doesn't feel attracted to him because he is actually NOT being him self around her. He is being a huge p**sy and way too much of a nice guy and will basically put up with ANYTHIGN with her and is "just happy to be there." If he was with just any random chick, he would act more "normal" and be him self, and would not put up with any ****, and would treat her like a little girl that she is and be sexual and what not, but NOT with this friend, hell, he probably won't even get hard when it comes down to it (if he is in that position) because he WORSHIPS this girl, and is OBSESSED with her, and doesn't really feel the "sexual" love, he is just infatuated. In response, she knows that "something is off" and she actually wishes deep down that he woudl just treat her like a normal person and be flirty and sexual with her and get her going... she WANTS to get off on him but as the things are right now, she can't!! It's like she is dating her brother!! that's probably how she is gonna feel if he makes that weak atempt to kiss her!!
Anyway, I HOPE it doesn't work out like this, but most of these situations usually do. Hell, if you want PM me and you can give the dude my number and he can call me and I can give him a sh*t ton of examples and advice, but it just may be too late lol