I married this Dragon King instead of my sister

In her past life, human princess Seraphina loved dragonslayer Cassian with obsessive fervor, forcing him to marry her—though his heart belonged to her younger sister. War erupted, the kingdom fell, and Cassian died pleading only to "never see her again." She perished in flames, vowing: *If given another chance, I will never cling to him again. Reborn on her wedding day, she makes a new choice—yielding Cassian to her sister and offering herself in marriage to the brutal Dragon King Vhaeros, to avert the coming war. Vhaeros intended to torture her to death as a pretext for battle, but her cold defiance on the torture stairs, her negotiations at death's door, and her kneeling to tend wounded dragon soldiers slowly melted his frozen heart. Meanwhile, Cassian realizes on the wedding day that it was Seraphina who went to the dragons—and past-life memories torment him. Awakening too late to his true love, he pursues her to the dragon realm, only to meet her icy farewell.As Seraphina and Vhaeros grow close, she uncovers the truth: the mark on his chest matches the young dragon she saved twelve years ago—at the cost of her own near-fatal wound, healed only by her mother's sacrificed life. She is the very one he has mourned for twelve years, building a shrine in her memory. Misunderstandings dissolve. Old enmity transforms into twelve years of destined redemption—two souls, reborn, finally saving each other.