Kinda sucks how everyone is so stressed out about them being engaged when they act and care about each other the way long-term lovers / soulmates do. Neither of them can be loyal to anyone else but to each other, that much is apparent even if they were married off to other people. 😂 Cousin marriages aren't so uncommon in history either. Everyone against their union is just worried at the fact that Miyuki and Tatsuya have more power between them than any of the 9 families combined.