Anne, the protagonist in The Couple Next Door, has a few traits that influence their relationships with others.
One, she is depressed. Two, she is loving. Three, she is considerate.
These traits influence her relationships with others. “She has postpartum depression, so she’s been taking medicine for it, but even so we decided to leave Cora in the house by herself because we didn’t want Graham to be alone on his birthday” Her depression comes into play here when they go back to their house after the party and Cora is gone. Since she already had depression before this, the loss of her daughter really made her sad and she started breaking down crying and getting mad at Marco.
Later, on page 15, Marco interacts with Anne, basically consoling her . “ ‘Anne I’m so sorry, I know this is my fault, I’m sorry’ but, she just pushed him off ”. Anne’s response here deepens a reader’s sense of her depression, and sparks a feeling of sadness.