Fantasy book where de MMC become a monster/demon with a red hand and the FMC reincarnated among her peoples

[ela]

hoping someone can help me find this book:

possible spoiler:

the story begins with the FMC in battle with an army of monsters/demons, if I remember well the FMC, with a helmet, braided hairs, and red clock (signature of her people) was overpowered by the leader of the monsters/demons and the moment he was going to kill her he stopped because her face was familiar, it turns out she was his lovers who died many years earlier and she reincarnated.

the MMC had a hand red like the blood, if I remember well it is red because the moment he turned a monster he had his hand soaked with blood (he was turned into a monster by a female goddess or something like that), and the reason he turned into a monster/demon was because of the death of his lover.
one of the book covers contains a female with a braid and another one a man-monster-like