Previous lesson from me too.
I was probably 16. I dated this really nice guy. He did everything right, sweet as anything, was always there for me, did anything I asked, etc. I walked all over him and said I loved him one day, the next day I told him to leave me alone. We broke up and went back out once or twice. I left him for someone else that treated me like crap. And I didn't get out of THAT relationship til I had to get a restraining order against him. Now, all this time, alot of s*** was going on in my life. My parents got a divorce, I was depressed and felt suicidal, was starting to fail classes, etc. The other nice guy kept coming into my life and I told him the same thing that this girl is telling you now. It was nice to have someone there, but I knew deep down inside, I would never love him more than a good friend. It hurt him and I knew I was in the wrong, so I broke it off. He did not take it well and started drugs, almost flunked out of school, etc. I had to think past my own selfish needs and hurt him... again, but breaking it off for good.
The last time I talked to him was several years ago. He told me that I was his first true love and that I had hurt him. I told him that I knew that and I was sorry. I was young, confused and stupid. We never went back out or anything. He changed and was not really the same guy I knew previously. He turned into this big player and cared more about material wealth, loose women and status more than anything else. So sometime people change for the better, sometimes for the worse. But I'm pretty sure that the reason for him ending up the way he did had something to do with me. Which is unfortunete.
When I was younger, I was a b****, never got broken up with and always got what I wanted for the most part. But I was a teenager then and had no clue about what really mattered in life and didnt take other people's feelings into consideration. Your girl knows deep down inside that things will never progress with you. She's holding on to you here and there so that she wont be alone. Girls typically do not appreciate "the nice guys" til they are older. You need to back away from her, tell her you'll still be a friend, but not in the way she wants or needs you to be. You need to move on and find someone who is going to appreciate you and love you the way you need to be loved as well. Even if things improve with her later on down the road and you want to get back with her, I'd be against that. Once an ex, always an ex. If it doesnt work out the first time, then more than likely, this time wont work out either.
She has issues to resolve, not only with her life in general but also within herself. Never think that you can protect them from grief, or help them to "change". Live your own life how you need to live it. She obviously cares more about herself than about you or else she wouldn't be stringing you along. Look for the signs, ie "You know, you should probably find someone else that will make you happy". That's guilt talking. And when you DO find someone, dont fall for the "well, I didnt really think you would go out and FIND someone." Dont' be someone else's play thing. Get past the guilt, get past being someone else's pawn and find someone that WILL be there for you. It's fine to have hang ups, but not toy with someone else in the process.