Ordered to Seduce the Beautiful Duke, But Unexpectedly, I'm the One Being Doted On!

Story :  "What do you say, Henrietta? Will you serve our kingdom not as its queen, but as the leading mistress of my harem?" One day, Prince Georges came to his betrothed Henrietta with that as a suggestion. It goes without saying that the engagement was broken off. Finally things can calm down... or so Henrietta thought until she received a new letter from her aunt. She is now tasked with going to meet with the current king's much younger brother, Lord Richard, and find some way to seduce him. From what people seem to know, he is an eccentric sort of man who loves to paint and stays cooped up in his manor in the countryside. However, the man Henrietta has been tasked with seducing is actually a handsome charmer himself...?!