I have a similar problem and a similar question... I had been going out with a girl that I really loved for the past two years, when she began to show interest in another guy. This guy originally wanted to date my girl friend, but stopped his advances after I began dating her. Things went well for a while until the last 5-6 months of our relationship, in which she began to spend an increasing amount of time with this other guy.
I gave her space and downplayed the situation in order to show her the trust I had in her and our relationship. But after a few months things between them became semi serious, with her often choosing to spend time with him over me. I confronted her one weekend and she told me that he told her how he truley felt and that he wanted to have a relationship with her. At this point I asked her to no longer see him or talk to him, because it was obvious that he wanted our relationship to end. She however decided that her "friendship" with him was more important than our current relationship and that is when I made the decision to end it. The decison was in no way an easy one and was a very painful one to make.
Through all this we have remained close friends and talk to eachother often... Recently she has made mention of trying to restart our relationship, but I have no intentions of doing so for now.
Am I leading her on by calling her on the phone and being outgoing to her? I don't want to hurt her anymore, but I don't know if still remaining close friends makes it more or less difficult for her to get past the relationship. Any thoughts would be greatly appreciated.
Sorry for hijacking the thread, but I thought it was releavent to the discussion.