The Red Nights at the Duke's Castle

From Tappytoon Official English Translations:

When Sorel Idris turns around to find a stranger in her home, she isn’t that surprised at first. After all, her father warned her this would happen. But when she detects the faint scent of blood in the air, she can’t keep her rabbit ears from popping out in shock. Her father failed to mention that her soon-to-be husband, Duke James Calier, was a vampire centuries older than her! On top of that, she discovers she’s the heiress to a considerable fortune. Sorel slowly adjusts to her newlywed life while attending the university of her dreams.