I would say because you like him you love to see him every day and thought of you not seeing him everyday upsets you. I am guessing you really want to be with him all the time.
My guess is because you feel lets say empty because you are not together with him but you want to but there is something in the way and you just can't be with him
I used to do the same thing over a guy at school since 10th grade. I used to walk home crying but only because he started dating and kissing this girl at my school in public, and you see I wished that were me. I was way to shy to go up to him and tell him I like him or ask him out or anything.
This other guy was exactly like how you cry over him, and he was at my youth group and 3 yrs older than me. After really pushing to get to know him but him not reciprocating/responding, I gave up and then used to come home after youth group boiling my eyes out in the car and then at home. I then started going and ignoring him to a huge extent, like not even glancing at him once. He made me angry, I stopped crying after a little while of going week by week but it just made me angry every time I even knew he was in the room. I stopped going, I forgot about him, and now he's a thing of the past. I just realize he didn't have enough confidence to speak to me, because before when he did briefly he used to stutter and get uncomfortable.
My advice is, if you don't have the guts to just come right out and say you like him and ask him out. Have nothing to do with him, over time you'll forget about him and the crying will be a distant memory. But if you see him constantly every single day, this is going to make you worse. You are pining over something that cannot ever become. Ask him out, or forget about him and delete him. I know it's hard, but you have to do this if you can't ask him at least even if he likes you.
This other guy was exactly like how you cry over him, and he was at my youth group and 3 yrs older than me. After really pushing to get to know him but him not reciprocating/responding, I gave up and then used to come home after youth group boiling my eyes out in the car and then at home. I then started going and ignoring him to a huge extent, like not even glancing at him once. He made me angry, I stopped crying after a little while of going week by week but it just made me angry every time I even knew he was in the room. I stopped going, I forgot about him, and now he's a thing of the past. I just realize he didn't have enough confidence to speak to me, because before when he did briefly he used to stutter and get uncomfortable.
My advice is, if you don't have the guts to just come right out and say you like him and ask him out. Have nothing to do with him, over time you'll forget about him and the crying will be a distant memory. But if you see him constantly every single day, this is going to make you worse. You are pining over something that cannot ever become. Ask him out, or forget about him and delete him. I know it's hard, but you have to do this if you can't ask him at least even if he likes you.