Sound like a bad case of infatuation/limerence. It's like being in love with the idea of being with someone without knowing who they are. If you can help it, you might want to stop shopping there. The longer you stay in that state, the worse you'll feel, especially when hope and low self-esteem gets mixed in.
I know it sounds kinda mean, but I've been through this recently and other times before, and it is not fun. I was lucky that my last crush quit since I don't have to see him anymore.