That makes sense, since there wouldn't really be a point to advantageous marriages if the world ended, and if Yggdrasil saves humanity she'll probably have offers left and right anyway. Also two brothers to help continue things.

I can see Takatora treating her as The More Nurturing Extension of Himself Who Cares For Micchy, partly because she is and partly because Takatora is probably influenced a lot by what society tells him girls do. A well-meaning and socially-stunted form of sexism, maybe.