The Devil Dragon's Substitute Bride

In order to save her terminally ill sister, she was forced to take the place of her selfish cousin and be sacrificed to the rumored cannibalistic and brutal dragon duke. However, she unexpectedly discovered that the "terrifying beast" was actually a peerless beauty. Not only did he dote on her after marriage, but he also allowed her to make a stunning comeback. She married another seemingly good man who treated her cousin poorly, and after learning about the heroine's life, the cousin went insane with jealousy.