
I think the fact that he had no doubts about marrying her, while she was having such a hard time thinking about it really threw her off. Getting married is a big deal and the fact that he might not have thought about it as much as she did bothers her to an extent.
He talked about being responsible, but what if she sees him marrying her as an obligation or something he "has to do" rather than something he "wants to do".

Bro.....
Shin has been through alot since childhood and now the issue with him being appointed a position too high for his status and the fact that the Wolfgang treats him differently makes him have this mindset that everything he does has to be perfect, especially when it comes to matters with the King.
Him suggesting Wolfgang marry and have a queen is surely a way to get into the noble faction and gain not only the officials favor but also the nobles. He isn't thinking about what he wants but he's thinking about the best way to get Wolfgang the approval of everyone else.
Every new upload just reminds me of how single I am