Idk but this? https://www.mangago.me/read-manga/lack_of_love/
I think ur talking about this one? It’s good! Cute
https://www.mangago.me/read-manga/fallen_star/
I reviewed it and it’s pretty similar. I wish I’m right. Hahaha( ̄∇ ̄")
https://www.mangago.me/read-manga/fallen_star/uu/iur_chapter-69/pg-1/#

Please help me find this Manhwa. I am pretty sure it was full colored. They were a side couple. A had unrequited feelings for B back in school. B was close to him but slowly started finding him annoying after noticing his feelings and A was always following him. So, B just lied that he was thinking of going to military after graduation. A went to army as well the following year but couldn't find B there. So, he asked his bestfriend to find B 's contact. Then he got B's number, when he called, B was talking with his peers in University about girls and stuff.A was heartbroken, he asked B, why did he do that to him. B realised what he had done was unforgivable.
Years later B became an idol I think. Then after finding A, he started pursuing him.