Frank loved her as a friend and was always trying to help her, make her happy, make sure she was looked after and was making the right choices. When it was thought by Frank’s on again off again friend, Joe DiMaggio that Marilyn was cheating on DiMaggio, Frank helped him stage a raid on a strangers apartment, thinking it was Marilyn’s lovers home and that she would be inside. The raid was a bust, and a law suit was filed against Sinatra and DiMaggio. DiMaggio ceased all ties with Frank after Monroe's death as he held him partly responsible. Sinatra gave Monroe a pair of diamond studded earrings valued at $35,000, gave her a poodle for company and moved her into an apartment building managed by Frank Sinatra's accountant to make sure she was doing well. Frank considered proposing to Marilyn in the last days of her life as he felt that no one would mess with her if she is Mrs. Frank Sinatra. Sinatra felt that if she were his wife, everyone else would back off, give her some space and allow her to get herself together. He never proposed as Frank like Peter Lawford, was put off by Marilyn’s disgusting personal habits which left stains on his furniture. He did, however, offer some advice. The weekend before her death, Sinatra reportedly tried to coax Monroe into starting her life over. "Why bother?" she responded. "I'm not going to be here too much longer."

At the same time Sinatra appeared to be her friend he also treated her meanly, as he did many women. He used Marilyn to fulfill his sexual desires and lead her to believe that a friendship with him would lead to marriage, but never did. The fact that his mother Dolly, liked Marilyn helped her to truly believe her fantasy. Marilyn was purely there to come running at his beck and call and that was it. One evening, drunk on champagne and tired of waiting for him to come upstairs to her bed, she wandered nude into the room where Sinatra and his friends were playing poker. Furious at her he shouted at her, "Get your fat ass upstairs!" Frank cared for her, and really did want her to turn her life around towards the final days of her life, but she wouldn’t listen so Frank decided that she needed shaking up and still wanting to be part of the Kennedy circle, Frank assisted the family in obtaining documents to blackmail Frank didn’t care that Marilyn might have seen it as a betrayal of their friendship and trust, as Frank was too starry eyed over the Kennedys and acted out of the illusion that it was in her best interests to make her wake up to herself and move on with life.

He didn’t want to change her, to fix her, rescue her. However, by autumn 1961 Frank had concluded that Marilyn was too much to handle, and backed away from their affair.