My Mortal Enemy is a novel written by Willa Cather in 1926. The novel revolves around Myra and her husband Oswald who return to their home in Illinois, USA to visit their relatives. Oswald soon receives silver-buttons for his shirt from an old acquaintance and asks his relative Aunt Lydia, who is visiting, to say they are from her to thwart Myra's jealousy. Myra then meets an old rich acquaintance who she envies and she then argues with Oswald, after which Myra goes to a visit a friend in Pittsburgh. It is clear that Oswald and Myra are not happily married and Myra is angry at their poverty. The story then goes forward 10 years where Myra is now bedridden and Oswald works full-time. Myra expresses regret over marrying Oswald as if she had not, she would have inherited her great-uncle's fortune. Myra is later found dead by the seaside. Oswald expresses no remorse about his wife as he loved her always despite her difficult behaviour. He later moves to Alaska and dies.
The book was written by the author to show how although love can exist between a couple, resentment and regret can still arise and this can ruin a marriage or relationship. This can only result in an end to the relationship, and in this story it ended with Myra's death.
The book was received well by critics and fans alike. Indeed, the back cover of the book contains a review which notes that the novel is 'a work whose drama and intensely moral imagination make it unforgettable'. The author, Willa Cather, is also a Pulitzer Prize-winning author.