Post a sad couple

akizuki and kusaka from winter cicada they can't be together due to a war between their clans and in the end they both commit suicide

I'd call this a sad couple in one sense of the word. Misa Misa x Light Yagami, Death Note.

I find them absolutely sad

SPOILER: when Nagaisa dies mostly and leaves Tomoya all alone with his daughter

Saddest couple ever

Atsushi and Rokka Shimao

Hakuouki_Shinsengumi_Kitan
Chizuru an hijikata-san
"But I will promise you this.Until the day I die,I will protect you and love you.I will be with you and I won't die until we finally are free."

Asuma and Kurenai

Jellal and Erza of Fairy Tail since they chose not to be together as Jellal's atonement for his sins (even though they love each other soo much~~)