Camping out here to find something like this as well ( ╹▽╹ )
Not ugly but plain looking with inferiority complex.
https://www.mangago.zone/read-manga/ame_to_kiss/
Chapters 1-2 of this anthology:
https://www.mangago.zone/read-manga/sekai_wa_kimi_de_mawatteru/
Oh and this one the brother has an inferiority complex and is not considered as good looking as the brother.
I believe his story begins in chapter 5 or 6.
https://www.mangago.zone/read-manga/sayonara_itoshi_no_my_friend/
BL with “ugly” or painfully average characters like Never Understand or Aitsu no Daihonmei