So did David Garrow, whose 1986 biography of King, Bearing the Cross, is full of references to King’s sexual escapades.
Garrow wrote about a number of extramarital affairs, including one woman King saw almost daily. According to Garrow, “that relationship … increasingly became the emotional centerpiece of King’s life, but it did not eliminate the incidental couplings … of King’s travels.”
He alleged that King explained his extramarital affairs as “a form of anxiety reduction.” Garrow asserted that King’s supposed promiscuity caused him “painful and at times overwhelming guilt.” (Bearing the Cross: Martin Luther King Jr. and the Southern Christian Leadership Conference. William Morrow & Co. 1986. pp. 375–6)
See also selections from Bearing the Cross here.
He remains an icon, of course. Even today I heard him quoted in a sermon. Nobody’s going to tear down any of his statues. Ever.