The royalty king

It's the start of the 1800s and you are the daughter of the British queen and king.
your mother named you after Queen mary ellen the third after her great great grandmother, you have a rival castle who are the rulers of the other part of Britain, for centuries they hated your family and your family used to hate them until you met the son of the rivals, you fell in love with him and he fell in love with you.

(This is inspired by my favorite aesthetic, dark academia)