Why can't I let go?

Why is it so hard to let go of someone who was never yours in the first place? It's been months, and I still catch myself growing unhappy over what could have been, what little we had. Every time someone mentions you, or I see your name, it feels like a punch to the gut. I want so badly to move on, let the past be the past, but I can't, and I have to see you again soon. If I couldn't get over you in the months I had without you, I don't know how I'm going to do it when I'm around you.

I just want to find my happy ending.