Liu Jing did it on purpose for You Changjin to hear. She's over forty. Making her care about some irrelevant facesaving is the kind of foolish thing only young people would do.
The first time Liu Jing met You Changjin, she already made him lose face. So saying such words in front of You Changjin doesn't come off as mean.
However, for Zhou Yuwen, it was the first time seeing the affable Aunt Jing showing such a mean side, and he felt a bit awkward thinking, Aunt Jing, didn't you hear him? He's my academic advisor, are you trying to mess with me on purpose?
Indeed, You Changjin didn't look too good at that moment. He's not a fool, and the words Liu Jing just said were clearly targeting him, but he didn't hold a grudge against Zhou Yuwen.
Teacher You's character is unquestionable. As a teacher, he has the broad-mindedness to nurture and educate. It's not the first time Liu Jing has disliked him, there's no need for him to be angry with a child.
But inside, he did feel bad.
