My school just read one third of the book so if your school read whole one, this answer may not be right.
First, she didn't care for him, she acted like a good person cared for a stranger. Are there any parents who didn't know where and what their sons do every day? (she said that Gregor should do something that day at very early time) (You understand me, right? Because my mother would wake me up at the last five minutes before I miss the bus) She also didn't have Gregor's key room. It shows that their relationship is not really deep.
