Nobody is a fault here. They are all victims of circumstances and society.
Society have enormous pressure on all this characters. One just HAVE to HAVE A CHILD, another is a SLAVE trying to save herself, one is a father that tried to not make his son the groom of a slave (the worst character in my opinion), one is a noble that don't have the courage to run away with a slave, etc etc.
Yes, this doesn't make any sense to me. How oblivious she is about sex, especially thinking is gross ..she is not a little teenager anymore, a non asexual person should have felt something with Frederick, considering how much affection was there. And now you tell me it was platonic with him? A simple teddy bear to cuddle? Really? I don't like this all "poor virging that doesn't know a thing and doesn't feel any sexual attraction" also because now he seems kinda like a groomer.
I really liked how the story started, and I didn't never understood why people were so mad about a cheating in a contractual marriage with no promises involved. It was a facade and it was ok for me that she, or he, had a real lover.