The theme of coping with grief and letting go is integral to the novel. Julie must grieve Sam multiple times, as she thought he was gone forever before the supernatural phone calls. Julie and Sam must both confront the truth of his passing and that they will be separated forever when the phone calls conclude. In the ending plot twist, Sam admits in his voicemail that he was also avoiding the goodbye:

‘I picked up because—because I needed you. I needed to hear your voice again, Julie. [...] Because I didn’t want to let you go yet. I never wanted to say goodbye, Jules. And I never wanted you to, either. That’s why I stayed as long as I could. So don’t blame yourself for anything. [...] I realize now I made it a lot harder for you to move on. And I hope you forgive me for that. [...] You are my entire world, Julie. And one day, maybe I’ll only be a small piece of yours. I hope you keep that piece. [...] I love you more than you can ever know, Julie. I’ll never forget the time we had together. So please don’t forget me, okay? [.