Is it normal to feel this way about him?

I've known a guy for 6 years, 5 of those years were spent as acquaintances.
I had thing for him in high school, but i never told him. Then, we started talking more and liking each other this year, but things didn't work out. I put the blame on life and work in general just getting in the way.

When we we're around each other flirting, hanging out, or kissing it felt like bombs we're going off in the background. He's the only person i've felt like this about.

I haven't seen him/talked to him in 3 weeks because i'm too nervous to text him just to say "hi, how are things?"
I suppose i'm just afraid he won't answer, or that i'm nagging him.

When i see him he still waves at me, talks to me, says hi, still flirts on occasion, acts super friendly and offers me a drink. So part of me feels like he still wants to be friends somewhat.

When things don't work out between me and someone else i usually stop talking to them and vice versa, yet i find myself wanting to stay in touch with him, and be his friend if nothing else.

Anyway, when i think about the two of us as friends or more i can't help but feel like there is something between us. The feeling won't go away either, even after knowing things aren't going to work out in that way.

Is it normal to feel this way? Have you ever felt like or been able to tell if something was between you and another person? Could you tell something was there?