What novel is the film "The End of the Affair" based on?

The film The End of the Affair is based on Graham Greene's novel The End of the Affair.

Greene published the novel in 1951. Set in London during and after World War II, it follows writer Maurice Bendrix, Sarah Miles, and Sarah's husband, Henry. The story combines romantic jealousy with questions about faith, guilt, obsession, and forgiveness.

Both major film versions carry the novel's title. Edward Dmytryk directed the 1955 adaptation, starring Deborah Kerr and Van Johnson. Neil Jordan wrote and directed the better-known 1999 adaptation, which starred Ralph Fiennes, Julianne Moore, and Stephen Rea. The 1999 film received several major award nominations, and Jordan won the BAFTA for adapted screenplay.

The novel draws partly on Greene's own relationship with Catherine Walston; the British edition is dedicated to “C,” while the American edition names Catherine. A common mix-up is treating the question as asking which film inspired the other. In fact, both the 1955 and 1999 films were adaptations of Greene's 1951 book.