at my wit's end

How is it possible that I miss someone who's not into me? Someone I don't even know well? If I stayed longer, I would have felt so lonely. So there's no desire to be back together but I don't want to cut him off entirely. I don't understand this when there's not much for me to gain; especially now since there's even less, cuz we're friends. Someone talk some sense into me. I don't fully understand this.