Having a sister or a friend is like sitting at night in a lighted house. Those outside can watch you if they want, but you need not see them.
The quotation highlights the relationship the sisters had or to an extent what they would want to have considering their different outlooks. Ruthie and Lucille have a really complicated relationship as sisters because of the traumas both have suffered throughout their lives. The narrative charts the complexity of sisterhood in that as much as they wish to be together to be happy they choose to lead separate lives. They harbor opposing perspectives hence they individually chase their desired life even though it does not bring the happiness they hoped for.
You never know when you might be seeing someone for the last time.
The narrative handles the themes of death and loss from the sisters’ viewpoint on how it impacts their mental health and lives. The girls first lose their mother to suicide and subsequently their grandmother, which leaves them with unresolved traumas. They find different coping mechanisms to deal with the losses in the family thus creating a greater rift between them. The assertion expresses her mental state in that she is constantly afraid of losing someone consequently developing agoraphobia.
