Fairly mundane speculation, but does anyone else think that Nanase's mother focuses so much on Nanase's eventual family role as a result of Noriko's split with Edward? Given that she's disowned her sister, we saw the same lightning when she was hiding family secrets, she dislikes Raven despite his high standards, and Raven is the reason Noriko focused so much on her career, it stands to reason. Admittedly, I originally dismissed her reasoning as being the stereotypical Asian mother, but it makes sense in universe, particularly if she wants to avoid talking to Nanase about magic so that she doesn't have to talk about Noriko.
Of course, I'm also assuming that Noriko seduced Raven (the irreconcilable difference caused by Raven above), not knowing that elves are sterile, in an attempt to have children who could carry on her magic legacy. But I don't imagine I'm the first to have said that.