Ru Mu Zhi Chen

Yun Su lives by a strict code of honor: whatever he receives will be repaid in kind. For most of their lives, this has meant seeking vengeance in battle against his nemesis, the Martial Regent. But when Yun Su finds himself on the brink of death, that same nemesis shows him unprecedented kindness by saving his life. For once, Yun Su has no idea how to reciprocate… until he finally settles on an idea: marriage!

(Source: Tapas)