After I Desperately Avoided The Annihilation Ending, My Party Became Unwell

Zenmetsu End o Shinimono-gurui de Kaihi Shita. Party ga Yanda.
全滅エンドを死に物狂いで回避した。パーティが病んだ。

Source

Our Party Nearly Wiped and Then Everything Went Downhill
Zenmetsu End wo Shini Mono Kurui de Kaihi Shita. Party ga Yanda.· 全滅エンドを死に物狂いで回避した。パーティが病んだ。
novel

Walker, a man reincarnated as an adventurer, is suddenly attacked in a dungeon by a high-level monster and realizes he's in the dark fantasy world of a manga he read in his previous life. Not only that, but he also isn't the protagonist—he's an ill-fated side character meant to die alongside his party to establish the setting's grim tone! Walker fights tooth and nail for his friends, and although he loses a leg and an eye in the process, he manages to prevent everyone's terrible fates. But as he adjusts to a new life with an injured body, his female comrades begin to act strangely toward him! (Source: Yen Press)