Gui Mushuang
She shouldn't doubt MuYi's judgement when it comes to his home and "family" affairs. I think it's odd that she's surprised that the girl is acting that way. She knows how incredible MuYi is and she also knows MuYi only seems to tolerate his, I'm assuming, step-grandmother? Why wouldn't the girl act haughty and rude, especially in a place she "thinks" she has more rights to?