EXCLUSIVE: Marilyn Monroe and Frank Sinatra — How Their Relationship Was Far More Than a Love Affair

In early 1954, Marilyn Monroe went on strike. She had been cast opposite Frank Sinatra in the 20th Century Fox musical The Girl in Pink Tights, but discovered she'd be earning $1,500 a week while Sinatra got $5,000, RadarOnline.com can reveal. The actress was a no-show the first day of shooting and ignored the studio's threats about suspending her.

Monroe and Sinatra would never appear on the silver screen together, but they did begin a love affair sometime after the studio scrapped The Girl in Pink Tights.

It was "a relationship that was intentionally kept out of the public eye," said Edward Z. Epstein, author of Frank & Marilyn: The Lives, the Loves, and the Fascinating Relationship of Frank Sinatra and Marilyn Monroe. "They had a great deal in common. They understood each other."

The pair had each known the heartbreak of love gone sour by the time they became close. "Frank was still married to Ava Gardner, but it was a tooth-and-claw relationship," said Epstein. "And Marilyn was a battered woman, still reeling from her pending divorce from Joe DiMaggio when she and Frank got together."

Sinatra's previous friendship with the Yankee slugger might have made him pause before making a move on Monroe, but after "The Wrong Door Raid," DiMaggio had largely stopped speaking to him.

Sinatra had referred DiMaggio to a private detective who broke into the wrong apartment in an attempt to catch Monroe with a lover in the final months of her marriage to the sports star. When the story was published in 1955, DiMaggio looked foolish and blamed Sinatra for the fiasco.

Eager to avoid more drama, Sinatra and Monroe kept their budding romance under wraps. "They both knew what it was like to live under the constant pressure to live up to their images. When together, the masks were off, they were free to be 'Frankie' and 'Norma Jean,' which is what they called each other," revealed Epstein.

The couple also shared a strong romantic streak. "Frank felt protective of her and loved playing her knight in shining armor," said Epstein. "And Marilyn, all turmoil aside, was deeply romantic. She was an outspoken Sinatra fan before they'd ever met. She used to play his music to get in the proper mood for a photo session or scene."

They never promised exclusivity, but by 1961, things had gotten quite serious between Sinatra and Monroe. "That summer, he did propose marriage. But according to Frank's closest friends, she turned him down," said Epstein, who believes Monroe wanted to give her relationship with DiMaggio one more chance.

"It was a love triangle that resounded with unforeseen and ultimately tragic consequences."

After Monroe's unexpected death from an overdose of sedatives in August 1962, DiMaggio banned Sinatra and his music from Monroe's funeral.

"I think it's safe to say that Sinatra felt guilty for not doing more to save her, although when Marilyn had her sights set on doing something, she did it," said Epstein.

"Later, Sinatra said he did believe Marilyn had been murdered. By threatening to go public about her relationships with John and Bobby Kennedy, she had sealed her fate."

One of the singer's closest friends, Jilly Rizzo, said Sinatra never got over her. "He said that Frank loved her, as much as he could at that time anyway," said Epstein. "He was devastated by the news of her death."