@Bambi
Spoiler!
After Rosalia is kidnapped she is saved by the marquis and she hears from him that the duke got severely injured after saving the princess.She feels like she can't go back to the duchy anymore, so she decides to leave with johannes. While they're in the carriage they're stopped by the duke who got news about her being with the marquis, he's still unwell but he came to take her back. She firmly refuses to go with him, he begs her and says that the princess is only family to him but she replies she will never go back to him. While Rosalia is at the marquis mansion she thinks about finding her family, johannes precedes her and reveals she is his lost sister. 20 years before, both his mother and sister disappeared but he now has proof she is part of the marquis family. The Duke starts appearing around Rosalia and she is annoyed and tells him that now she will live as part of the marquisate and she doesn't like him anymore. As proof she asks him to try smelling her scent, and when he can't smell anything but doesn't know she actually learned from johannes how to block it.
Well I think one reason might be she doesn't want to appear as a man anymore because it stains Duke’s reputation as a "homosexual" and everyone misunderstand their relationship. Or maybe she is pis*** he didn't listen to her and prioritized the Crown Princess when he too knows that Crown Prince will come to save his Fiancée 🤷🏻♀️but I agree with your opinion that is her love for him so shallow that she doesn't bother listening to him 👀
I like to post spoilers for the stories I find interesting because I don't have much time to read novel due to busy schedule
you will find me in most romantic historical manhwa comment sections 
you will find me in most romantic historical manhwa comment sections 
