I am (was) in the same situation.
Unless people want me to re-type the whole situation... I'll just give a overview on this topic.
I think LJBF - LFRN/LTR is possible. I have seen it, and the best relationships that I have seen are when two people begin off as friends.
Its possible, but you must be willing to stick it out for the long haul. Life's best things, are the things that you work the hardest for.
BUT, BUT, you must continue to see/look for other possibilties. You MUST be willing to walk away, only then, will she see what she is missing. Its a paradox, and it sucks. But thats life.
If she comes running back, don't take her. Push her away (kindly) and move on with your life. Perhaps in the future you two can 'connect', it happens, but it doesn't happen that often.
I have fallen into this trap.. but with a good girl (I dont' think she had evil in her body). But, she didn't date, period. The end. She had a lot of guy friends, but she didn't date any of them. My take was that she was hurt in the past, and she didn't want to set herself up for another emotional pain. She was confused, very confused.
My advice to all guys who meet these kind of chicks: Put them on the back burner. Keep in touch with them, but don't make them a prime target.
Unfournately, when these girls do come around and start dating again, it won't be with you, but with someone else, who hopefully won't dump them on their ass.
[AFC Mode] I feel sorry for these girls, they might make good LTR people, but they're too confused to take anymore risks.[/AFC Mode]