Goinsugiru Oji Sama Ni Shuchaku Sarete Nigeraremasenga Shiawasedesu.

https://www.cmoa.jp/title/342592/vol/4/
https://ebookjapan.yahoo.co.jp/books/932463/A006338574/

Leticia works as an assistant librarian at the Royal Library. One day, she reunites with Crown Prince Patrice, who has just returned to their country after serving in the suzerain kingdom. The moment they meet again, Patrice begins passionately courting her.