Seriously, why do you think that a workplace "hookup" ever be a good thing? I cant find a scenerio in my mind that this ever works~ Im sure there are ten examples where it does, but this just sounds like a disaster to me. ( Unless its just about one thing, and this gal doesnt sound that way to me, nor do you....but a long term relationship with a coworker.....Ohhh...Not the best for either of you)
Just my 2 cents.