It may well be a case where the gossip was more titillating than what actually happened between Monroe and Kennedy.
"The first time Marilyn and JFK were confirmed to have been at the same place at the same time was at the April in Paris Ball on April 11, 1957, at the Waldorf-Astoria Hotel in NYC; Marilyn was there with her then-husband, playwright Arthur Miller, while John attended with his wife, Jackie, and his sister, Eunice Kennedy Shriver. Both of them were photographed extensively throughout the night, but no meeting between them took place at that event. It's more likely that John and Marilyn first met at a dinner party hosted by actor Peter Lawford in 1961. Peter was married to John's sister Patricia, whom Marilyn became friends with while filming Let's Make Love. They also had a mutual friend in Frank Sinatra, who was a member of the Rat Pack with Peter and who briefly dated Marilyn after her divorce from Arthur Miller.
Multiple Marilyn historians, including respected biographer Donald Spoto, who wrote the 1993 book Marilyn Monroe: The Biography, allege that the most plausible time that Marilyn and JFK could have had a sexual encounter was during a party at Bing Crosby's home in Palm Springs, CA, on March 24, 1962. Marilyn's masseur and close friend Ralph Roberts told Spoto that he received a call from the actress asking him for massage techniques for muscles of the back, and that he "heard a distinctive Boston accent in the background" before Marilyn handed the phone to President Kennedy. Ralph Roberts added, "Marilyn told me that this night in March was the only time of her 'affair' with JFK. A great many people thought, after that weekend, that there was more to it. But Marilyn gave me the impression that it was not a major event for either of them: it happened once, that weekend, and that was that."
http://thepoliticalforums.com/thread...79#post2548879