Thanks for the new chapters! Definitely, Yuurin should have forgotten about the whole Anti-Affair Operation and just be herself. It's super effective!
@MangaLover6 The current king is the son of a lowly consort who suffered a lot due to harem intrigues, and he ended up growing in the frontier and leading a military life (he only took over the country because of a succession crisis). Because of these experiences, he values loyalty, hard work and austerity, and was never interested in the prim and proper ladies every noble family wanted him to marry. The hiring of a "fake bride" like Yuurin was a plan to fend off marriage proposals for the time being. However, little by little, she impressed him by showcasing the qualities he values, not to mention that her reactions were hilarious. As Arararanya has said, curiosity became love and here we are.
Ok, it was more complicated than that, and the turning point was the Black Marketeer Arc (ch. 56 - 71), but I think this little summary is close enough.