Uwasa no Funou Koushaku ga, Jitsu wa Zetsurin deshita.

Leticia, the daughter of a marquis, loves books and reads books both domestically and internationally. She is not good at real men, and she is in love with her Oshi'' from the world of novels. But one day, her new book, which she was looking forward to, turned out to be her pusher''!
In the midst of her disappointment, her father decides to marry her to a duke who is seven years older than her.
Although Leticia complains that "real men are absolutely impossible," she is unable to disobey her father and heads to see Duke Sieghardt, who is rumored to be "impossible," but... what appears before her eyes is A duke wearing a "mask" who looks exactly like the "favorite" character who was supposed to be dead...?

https://www.cmoa.jp/title/269364/