Notes from Wikiquote
[L]ife was not so much "one damn thing after another" as "one damn thing over and over" | As paraphrased ("she had sent [...] a half-comic note, complaining that...") with quoted phrases in Jean Gould, The Poet and Her Book: A Biography of Edna St. Vincent Millay (1969), p. 198 | [L]ife isn't one thing after another, it's the same thing over and over | As paraphrased ("she writes that...") and apparently Bowlderized in Miriam Gurko, Restless spirit: the life of Edna St. Vincent Millay (1962), p. 197 | [I]t was not true that life is one damn thing after another — it was one damn thing over and over | As paraphrased ("Edna had written [...] that...") in Joan Dash, A Life of One's Own: Three Gifted Women and the Men they Married (1973), p. 189 | The paraphrase by Dash appears to be the origin of later popularly attributed variants, e.g. | It is not true that life is one damn thing after another. It's the same damn thing over and over. | As attributed without citation in Psychoanalysis Today: A Case Book (1991) by Elizabeth Thorne and Shirley Herscovitch Schaye, p. 93 | It is not true that life is one damn thing after another. It's the same dang thing over and over again. | As attributed without citation in The Last Word: A Treasury of Women's Quotes (1992) by Carolyn Warner