The letter reads: ''Why don’t you leave suburbia for once—come and see me—either here—or at the Cape next week or in Boston the 19th. I know it is unwise, irrational, and that you may hate it—on the other hand you may not—and I will love it. You say that it is good for me not to get what I want. After all of these years—you should give me a more loving answer than that. Why don’t you just say yes.''

White House secretary Evelyn Lincoln kept the president's unofficial documents, including sketches and the letter which was never sent to Meyer. The letter has come from the estate  of Robert White, who bought several of JFK's possessions from Lincoln.

Kennedy first met Meyer at high school in Choate. In 1954 the pair were reacquainted when the Kennedys moved to Georgetown. A socialite and painter, she became friends with Jackie whilst Meyer's husband was a CIA agent. Once Kennedy was in office, Mary is said to have visited the White House frequently when Jackie was out of town. Nevertheless, they managed to keep the affair secret.

Kennedy did plan to be in Boston on October 19, where he appeared at a Democratic Party Fundraiser, 'New England's Salute to the President,' at the Boston Armory.

Robert Livingston, executive vice president at R.R. Auction, commented on the president's cavalier attitude: ''It’s something you wouldn’t expect to see from a president. And the fact that he didn’t send it, obviously he came to his senses.''

A year after the letter was written by JFK, Meyer was shot and killed in Georgetown on October 13, 1964. Her death has still not been resolved.

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