When did Franklin d roosevelt become unfaithful to wife Eleanor?

Franklin D. Roosevelt's infidelity began in the early years of his marriage to Eleanor Roosevelt, with one of the most notable affairs occurring with Lucy Mercer, a social secretary, in the early 1910s. Their relationship became particularly significant during the 1920s, and Eleanor discovered the affair in 1918, which nearly led to their separation. However, they ultimately remained together, maintaining a complex partnership throughout their lives.