The novel deals with themes of love, regret, suffering, pain, and duty. On one hand, Frome has a duty to his sick wife – to take care of her and ease her suffering. One character notes as such, commending him for taking care of his wife in her time of need, and his own parents before that. His duty is at loggerheads with his heart, which yearns for Mattie. He hopes for time alone with her and reacts negatively when his wife wishes to send her away.
His love for her directly leads to the ending of the novel, which deals with the theme of making a decision and living with it, irrespective of want or desire. Ethan and Mattie make a decision which leads to an irrevocable change in both of their lives – one that, almost by necessity, forces them to be together for all time.
Unlike her contemporary, Charlotte Perkins Gilman, author of Herland, a utopic novel, Wharton goes in the other direction. Instead of portraying a utopic situation, she has it devolve into the worst of all worlds; the characters get what they want in the worst way.