According to her Wikipedia article, "...In 1913, at age 21, Vita married the 27-year-old writer and politician Harold George Nicolson (21 November 1886 – 1 May 1968), nicknamed Hadji, the third son of British diplomat Arthur Nicolson, 1st Baron Carnock (1849–1928). The couple had an open marriage. Both Sackville-West and her husband had same-sex relationships, as did some of the people in the Bloomsbury Group of writers and artists, with many of whom they had connections..."
She had affairs with Rosamund Grosvenor, seen in this Subalbum, novelist Violet Trefusis, Alice Keppel's daughter, Virginia Woolf, and others.
Her marriage produced a son and was apparently congenial.
Her mother's Subalbum is here.