It's the way you chose to put it, yman. You sound like you dislike her and yet you want to fuck her - as women we find that disturbing. Can't you see that?
You have no idea how many times I have heard a man say to me or another woman (or about another woman) "nothing wrong with her that 10 minutes on the end of my cock won't cure"... for a start to those guys I often say "10 minutes?" and laugh in their faces - but actually it is a very insulting thing to say about a person - and a very arrogant thing. And that is how you came across. You seem to be implying now that we have taken you up wrong - fine - I'll take you at face value. Let's start again.
You have no idea about this girl, you sound like you don't know her well at all - perhaps her boyfriend is a phenominal lover, perhaps he is just right for her, perhaps he isn't, perhaps, perhaps, perhaps - thing is, he is her boyfriend, they are a couple and you should attempt to interfere with that.
So you have a fantasy that a slightly stuck up (to your mind) girl is going to have the time of her life bouncing up and down on your cock and after that mind blowing experience she'll be a changed person. You ask do we think you have a shot. No. No I don't. I think you don't know her anything near well enough to really say what she is like at all - so your images of what she is like and that she needs changing at all are probably way off the mark. She maybe a delightful individual with her friends and bf outside of work - she may be a little demon in the sack. You really don't know.
If it really is just a fantasy I don't see any harm in having it - but don't act on it - it'll just be embarassing for both of you. And please be aware that woman don't find being thought of in those terms at all flattering.
Is that more helpful to you?