Example... Haruka tooki le
care for some sad gl oneshot? ;) https://www.mangago.zone/read-manga/only_need_to_love_once/
'Timeless melody'
'Efforts never betray'
This witch of mine !
…
.
.
.
.
.
Spoilers for others
.
This witch of mine has a happy end tho, the main characters at the start of the story find each other again and get together
Dunno if it fits the bill but here ya go
https://www.mangago.zone/read-manga/bound_to_be_fools/
https://www.mangago.zone/read-manga/sleeping_dead/ (recommend)
https://www.mangago.zone/read-manga/ouroboros/
10 years i loved you the most
Manhwa's with NO happy endings.. Like the MC died or the two of the main couple didn't get together, smth like that. Like A sad ending. I want it short but had a great plot