Jackie Kennedy wasn’t impressed by one Hollywood heartthrob and his future Material Girl flame.

In his new book "Jackie: Public, Private, Secret," author J. Randy Taraborrelli claims the former first lady had a brief fling with Warren Beatty in 1978. At the time, the widow of President John F. Kennedy and Greek shipping tycoon Aristotle Onassis was a book editor for Doubleday eager to score top stars willing to write their memoirs.

"When I learned the reason why Jackie was disenchanted with Warren, it made me laugh because we all had that experience," Taraborrelli told Fox News Digital. "We often go out with somebody and think they’re going to be one thing, and they’re totally not. It’s disappointing… And this brief fling says so much about Jackie’s commonality. It’s an experience we can all identify with."

Taraborrelli’s book, published on Tuesday, is based on nearly 25 years of research and hundreds of interviews with friends, family and lovers. It also references unreleased papers from the JFK Library, including diaries and oral histories.

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Beatty once wanted to play the president in the 1963 film "PT 109." John, who had the final say over the role, chose Cliff Robertson to play him before he was assassinated that year at age 46.

But by the time the mother of two had her eyes on Beatty, the 41-year-old was a sought-after star who was rumored to have hooked up with "almost every major female star in show business under the age of 50." His biographer claimed that Beatty bedded about 12,775 women before he married Annette Bening in 1992 and became monogamous.

Kennedy, who found the actor interesting, went out on a few dates with him. One member of her staff described seeing Beatty chatting with Kennedy’s son, John F. Kennedy Jr., at her kitchen one morning "as if it was the most normal thing in the world."

But Kennedy wasn't impressed by her new beau and instead described him as "self-absorbed." She told friends how, for hours, they only spoke about him and his goals.

"Then, just before he kisses me good night, he looks at me and says, ‘So, how are you doing?’" she allegedly told pals. "And by that time, I’m totally done with him."

"Warren couldn’t stop talking about himself," Taraborrelli chuckled. "He spoke about himself, his career, all the movies he’s making, and so on. And Jackie was just so over him. She just didn’t care anymore… This is not a slight on Warren. It’s kind of understandable. He was at a high in his career. He was making big films. And of course, all he wanted to do was talk about his movies."

If the dates ended in sex, Kennedy thought "that was fun," Taraborrelli’s book alleged. But after a few times, she was "done" with that, too.

Taraborrelli claimed a close friend asked Kennedy how she would rate his bedroom skills.

"Oh, he’s fine," Kennedy allegedly replied. "Men can only do so much, anyway."

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She noted that perhaps if they had met 10 years earlier, she would have had a lot more fun. However, he entered the picture "when I had other things I was dealing with, and believe me, having sex wasn’t one of them."

Taraborrelli alleged that Beatty faced his own disappointment because he was expecting someone more "interesting." Instead, he found Kennedy to be more "like a housewife" than the glamorous queen of Camelot.

"She’s like a suburban mom," he allegedly told Truman Capote. "All she cares about is her kids and whether or not people at her job like her. [I always thought] Jackie Kennedy would be a lot more exciting."

The relationship was doomed from the start.

"When Warren met Jackie, she was working at a publishing company, and she was raising her children," said Taraborrelli. "They were on different paths. So, the relationship was not going to go anywhere. Jackie said she felt the relationship lasted two weeks longer than it should have. Jackie has only been with really fascinating men, so I believe she had her own standard that he just didn’t meet… And the truth is, when you’re out in the dating world, you get a few duds. I think that Warren was one of them."

The fling ended right before Christmas of that year. Kennedy was hosting a holiday party at her home when Beatty allegedly showed up with his posse, which the stunned hostess wasn’t expecting. The final nail on the coffin was hammered when Beatty allegedly mentioned to Kennedy’s stepbrother, Hugh D. "Yusha" Auchincloss, that he was sleeping with her.

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"When he told Jackie about it, it was the final straw with Warren," Taraborrelli wrote.

A spokesperson for Beatty, now 86, didn’t immediately respond to Fox News Digital’s request for comment.

It wouldn't be the last time Kennedy faced disappointment with a major star.

It was 1988 when John Jr., who was 28, began dating Madonna, who was 30. According to Taraborrelli, the blossoming romance "was a source of contention" between the "Sexiest Man Alive" and his mother.

For years, many speculated the matriarch disapproved of her son’s fling with the pop star because she famously emulated Marilyn Monroe, her husband’s alleged mistress. But Taraborrelli insisted Kennedy wasn't thinking about the late blonde bombshell, who died from an apparent overdose in 1962 at age 36.

"It was very simple – Madonna was married to Sean Penn," he explained. "That was enough. Jackie did not approve of infidelity at all. Jackie’s mom Janet suffered through a bad marriage to her father, who was unfaithful the entire time. That affected Jackie a lot."

But Taraborrelli pointed out in his book that like Monroe, Kennedy also thought Madonna wasn't "that smart."

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"There are millions of intelligent women on this planet, John," Kennedy allegedly told her son. "Why must you go out with the only one who calls herself a ‘Material Girl?’"

"Oh, really, mummy?" John countered. "Who in this world is more materialistic than you?"

It was a statement John Jr. regretted. Still, he was determined to get his mother's blessing.

John Jr. convinced his mother to check out his girlfriend on stage. At the time, she was performing in the Broadway play "Speed the Plow." Taraborrelli wrote that Kennedy attended the show with a Doubleday colleague wearing a red wig in hopes she wouldn’t be recognized.

Despite her appearance, Kennedy refused to go backstage and meet Madonna. She argued to her pal that she "didn’t want to give Madonna the opportunity to promote a relationship between them."

"I’m not going to validate the relationship by meeting her," she added.

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Taraborrelli said Kennedy went in disguise "for John."

"Madonna was somebody that Jackie might have found interesting if she took a moment to get to know her," said Taraborrelli. "But the relationship only lasted about six months. It was casual in the sense that it never developed into anything more."

Madonna’s divorce from Penn was finalized in 1989.

In 1991, Madonna connected with Beatty, who was 21 years her senior, during filming of their comic book film "Dick Tracy." The relationship didn’t last much beyond the premiere, People magazine reported.