why is it so hard to let go?

Ok so i met this boy about 7 years ago. He's best friends with my cousin but we all played a sport together so hung out more, alot more. His family & my family are close as well. But anyways, I've got this biggest "crush" on him. I can't seem to figure out what it is about him that's got me going crazy. I literally can't stop thinking about him. I see him every so often, but i have no clue on his feelings for me. At one point i thought it was mutual but then we drifted apart after High School & now i can't make out how he feels. I am the shy type of girl, so i can't just go up to him and ask or anything like that. So, how'd you recommend me to finding out? plus, i'm also afraid that if i do approach him (in any way) that he won't have this mutual feelings, feel all weird around me and then that'll just break our friendship. I don't want to lose our friendship. What do i do?
It's been over 7 years since i had these feelings for him. Like it's crazy!!! I've tried to just get over it but i can't idk why.
Help, please! Adivce?!

Thank you.

It's so hard to let go because you don't let go, if you look at the whole thing again, he's not the only man in the World.

ok, so i realize that he ain't the only guy on earth. But that's what i'm trynna say. I know there's other guys, so i ahve tried to get my self away from him. I had a bf a yr back that when we were going together i still, no matter what, couldn't get my mind off of this "crush" of mine. It's so hard. sometimes i feel so stupid and weak because i can't stop thinking about him and what now. But thanks!