Aaron sighed in frustration, "Anna, please don't say that you are sorry. Like what Mom said to you, there is nothing for you to say sorry for." He hates it when his sister is saying that she is sorry when there is nothing for her to say sorry for. She is not the one who's in the blame, it's him, their father, and mother. "It's me who has to say sorry to you."
Aaron admits that he is being stubborn and childish. Between him and his sister, his sister is much more mature than him. She looks at both sides of the story before making a choice. She knows the sacrifices their father had made and what he and their mother feel about it.
Anna is not picking sides, she is only doing what her heart tells her to do. Their father needed a chance to prove himself, and she gave that chance to him. It's clear that she is still angry about the choice they had made, but she put emotion aside and has about the matter rationally.