Roosevelt had various extra-marital affairs, including one with Eleanor's social secretary Lucy Mercer, which began soon after she was hired in early 1914. In September 1918, Eleanor found letters revealing the affair in Roosevelt's luggage. Franklin contemplated divorcing Eleanor, but Sara objected strongly and Lucy would not agree to marry a divorced man with five children. Franklin and Eleanor remained married, and Roosevelt promised never to see Lucy again. Eleanor never truly forgave him, and their marriage from that point on was more of a political partnership. Eleanor soon thereafter established a separate house in Hyde Park at Val-Kill, and increasingly devoted herself to various social and political causes independently of her husband. The emotional break in their marriage was so severe that when Roosevelt asked Eleanor in 1942—in light of his failing health—to come back home and live with him again, she refused. He was not always aware of when she visited the White House and for some time she could not easily reach him on the telephone without his secretary's help; Roosevelt, in turn, did not visit Eleanor's New York City apartment until late 1944.
Franklin broke his promise to Eleanor to refrain from having affairs. He and Lucy maintained a formal correspondence, and began seeing each other again in 1941, or perhaps earlier. Lucy was with Roosevelt on the day he died in 1945. Despite this, Roosevelt's affair was not widely known until the 1960s. Roosevelt's son Elliott claimed that his father had a 20-year affair with his private secretary, Marguerite "Missy" LeHand. Another son, James, stated that "there is a real possibility that a romantic relationship existed" between his father and Princess Märtha of Sweden, who resided in the White House during part of World War II. Aides began to refer to her at the time as "the president's girlfriend", and gossip linking the two romantically appeared in the newspapers.