After I married a vampire, he regret

Human princess Katia is trapped in a one-sided crush on knight Alonso, who only favors her scheming half-sister. When the century-old vampire sacrifice approaches, haunted by tragic memories from her past life, she chooses to take her sister's place and head to the vampire realm to end her painful love. Alone in the dangerous vampire castle, she catches the eye of Lestat, the 9,000-year-old vampire lord. Her rare blood makes her irreplaceable to him. Wracked with regret, Alonso tries every means to win her back, even allying with werewolves to stir up conflict. Torn between her remorseful old flame who brought her endless pain, and the vampire king who cherishes and protects her wholeheartedly, Katia navigates tangled conflicts between humans, vampires and werewolves, and finally makes a choice about love and her own destiny.