Hana Himeru Kimi no Meteor

From Shortcake Club:

"On that fateful night, I became the cursed monster’s bride—"

Stella, the eldest daughter of the Quinwich Viscount family, is an adopted child but lives happily with her kind-hearted family. However, one day, her younger sister Lilinette is chosen to become the "monster's bride." Every hundred years, a cursed monster imprisoned in a castle requires a sacrifice. To protect Lilinette, Stella decides to take her place. The monster she meets there is a bloodstained vampire named Ravi.

This is the heart-wrenching and beautiful story of a devoted girl and a vampire who has given up on everything, bound together by love and curses.