Complex sentence: While they stay there, George and this sister agree that he will stay living there when Anne moves on with Robbie to Los Angeles; he is unhappy with the fact that Anne does not know things like his favorite color or his favorite book.
Split into simpler sentences: While they stay there, George and this sister agree that he will go on living there when Anne moves on with Robbie to Los Angeles. He is unhappy that Anne does not know things like his favorite color or his favorite book.