How do I fall out of love?

I am deeply and completely in love with a man that doesn't want me as anything more than a friend. We have had a tumultuous relationship for almost 2 years now. We went from friends to lovers to live-ins to ex-lovers/live-ins to friends + lovers which is where we seem to be right now. He has made it very clear to me that he is actively looking for his "soul mate" and she is not me. I have read his Personals Ad and the woman he describes as his ideal IS ME!!! with one exception -- the word "slender". I am not obese but nor am I pencil thin. Everytime I ask him why he is throwing me aside he says he "doesn't know what to tell me". I have never been so deeply attached to anyone or anything in my entire life as I am to him but I can't keep sticking pins in my eyes. I am so hurt and feel so worthless I know I have got to get over him but HOW?????