Carson and Reeves McCullers divorced in 1941. After separating from Reeves she moved to New York to live with George Davis, the editor of Harper's Bazaar. She became a member of February House, an art commune in Brooklyn. Among her friends were W. H. Auden, Benjamin Britten, Gypsy Rose Lee and the writer couple Paul Bowles and Jane Bowles. After World War II McCullers lived mostly in Paris. Her close friends during these years included Truman Capote and Tennessee Williams.
In 1945 Carson and Reeves McCullers remarried. Three years later while severely depressed she attempted suicide. In 1953 Reeves tried to convince her to commit suicide with him, but she fled and Reeves killed himself in their Paris hotel with an overdose of sleeping pills. Her bittersweet play, The Square Root of Wonderful (1957), drew upon these traumatic experiences.
In The Member of the Wedding (1946) McCullers describes the feelings of a young girl at her brother's wedding. The Broadway stage adaptation of the novel had a successful run in 1950–51 and was produced by the Young Vic in London in September 2007.
McCullers suffered throughout her life from several illnesses and from alcoholism. She had rheumatic fever at the age of 15 and suffered from strokes that began in her youth. By the age of 31 her left side was entirely paralyzed. She lived the last twenty years of her life in Nyack, New York, where she died on September 29, 1967, at the age of 50 after a brain hemorrhage; she was buried in Oak Hill Cemetery.
McCullers dictated her unfinished autobiography, Illumination and Night Glare (1999), during the final months of her life. Her home from 1945 to 1967 in South Nyack, New York, was listed on the National Register of Historic Places in 2006.