This whole thing reeks of being a giant clusterfuck. The fact that they're making her commit bestiality aside, the fact that her parents tacitly agreed to send one of their daughters to her death is unthinkable to me. Her sister looks like a kind person, but she also agrees with their actions being logical. Does that mean if she were in that place in the future, she'll choose to sacrifice her future child to remain a noble?
Sigh, I wish Astina will blame them. But she won't, and this makes it harder. It's easier to hate someone than to understand their circumstances.