I went through something similar recently. I don't know how or why it happened, but one day I realized that a friend I had had for over 50 years had stopped wanting to be friends. I miss her, but I'm not going to let her absence keep me from trying to make other friends. I have great memories of our time together, but I know I can't make her want to go back in time. I guess I'm saying that I hope you find peace.
