In the end, all the characters in Everything I Never Told You survive– except Lydia

In the end, all the characters in Everything I Never Told You survive– except Lydia. James and Marilyn reconcile, emotionally and physically. Hannah begins to receive love and appreciation from her mother especially. Nath gets to punch out Jack, go to Harvard, and eventually (as one line of the novel reveals) becomes an astronaut. But Lydia dies. Why was she the family’s fulcrum for suffering in the years leading up to, and why did she drown in the lake that night? Why did the author choose to have this family suffer the loss of the “favored” daughter, and the daughter to become the eternal victim? This is a fiction, after all, and the author could have chosen to let the character live. But would Lydia’s survival been unbelievable? Was her death necessary for the others to survive psychologically and spiritually?