From https://www.reddit.com/r/manga/comments/9fjckr/disc_hoshino_me_wo_tsubutte_epilogue_volume_13_end/ :
"Basically, the main character wimps out and dumps his girlfriend because she doesn't need him once he stops wearing makeup. She becomes so disgusted she refuses to even acknowledge his existence anymore. His confidence shot, he withdraws into himself and all of his friend abandon him to go back to their old cliques and all the girls who liked him realize that they were too good for him. The series ends with him hoping that he can make at least one friend."
Also this: "The manga originally ended with almost all the relationship broken, each character finished in their own separate way, it feelt like a start from zero... that pissed off a lot of fans, because the best thing about this manga was undoubted seeing how the characters matured and changed interacting with each other, none of them were perfect, all have bad days, childish or fears. So ending with a clean slate was even worse than a sad-bad ending."