CV, I just the read the first page and the last couple, so forgive me if I missed something crucial. I won my wife from a sort of similar situation. Two rules. Be honest about how you feel to her even though it will seem counterproductive sometimes. Don't fear the friend zone. In fact, make sure that you are her best friend. It takes time...painful time, but you are giving her a very real and solid alternative to the status quo and success is inevitable. At least it was for me. She knew I wanted to marry her and eventually she said yes. No dating ever. We just skipped straight to the good part. I have been the happiest guy in the world for 14 years now.
Good luck!
Jeb
