Am i the only one thinking her guard again the duke are pretty reasonnable? Don't forget she only know him as someone cruel and heartless, someone who would feed his son poison and torture his ennemies on a regular basis, and she even saw him transport a corpse (or what she believe to be one) in the middle of the house (which by itself could cause trauma) like it's a everyday occurence.
And you expect her to open up after so little time togheter ?
I would add that every time they meet, he didn't show any of his feeling, in her place i will more likely imagine that he's thinking whether or not he should kill me rather than imagine he's falling in love with me.