is it possible to "need" someone in your life?

So this may be a strange question but here goes; There's this person i know. and we're best friends. nothing more but nothing less. he's helped me through some of the darkest patches through my life. he's the reason i made friends when i started high-school, he's helped me (unknowingly) with self harm recovery to great amounts. I've almost formed this habit of having him to comfort me when im upset, and im not even sure if that's possible. On Friday we hadn't seen each other in 21 days and it was making me very irritable i was texting him asking him why he wasn't in school and i was worried about him alot, i was in a bad mood because of it, i really wanted him to be there for me and hold me at that minute and it was just making me generally upset; even though i was in a good mood when i thought he was coming. Why am i so upset when he's not here for me? even just to see him as a friend; why do i get so upset that i can't talk to him? is it possible that i need him in my life to be happy?