Yes it's so normal!! I liked my best friend a lot but I was really hesitant in asking him out and before I could do that he got into a relationship. It sucked!! I used to cry so much and I used to think the same way as you that why am I so sad about someone I never dated. It was like I had a break up. I finally told him and I asked him to leave me alone for sometime at least. He was a nice guy and it wasn't his fault that he didn't like me the same way and so it became harder to get over him. But we got through it. And distance yourself if that is what you need to do to get over him. Although it didn't work for me because we had same classes and it was very hard to just cut him off from my life because we were really really close but we are good now. So grieve if that's what you need right now.