Bonnie Bartlett Daniels has been married to William Daniels for 72 years, but the actress insists that their union is "hardly a fairy tale."

The "St. Elsewhere" star just released a memoir titled "Middle of the Rainbow." In it, she details her rise to stardom, how she coped with childhood abuse and other personal tragedies, as well as the story behind her decades-long relationship with the actor. The two-time Emmy winner has been married to Daniels, recognized by many as Mr. Feeny from "Boy Meets World," since 1951.

"I guess it was a little bit of an open marriage at first, but that was very painful," Bartlett Daniels told Fox News Digital. "That didn’t work well. And it was a time when people were doing that. It was at a time in New York when there was a lot of sex and a lot of people doing all kinds of things, you know – very free. But I don’t know if there was a lack of commitment a little bit, and that’s not good. So there was a lot of pain connected with any transgression, with any extramarital thing."

William Daniels and Bonnie Bartlett Daniels smiling

William Daniels and Bonnie Bartlett Daniels have been married since 1951. (Getty Images)

"It was very painful for the both of us," the 93-year-old shared. "But it was something we had to go through because we never went through it. When we got together I was 18. Bill was my first boyfriend… We just had to go through all that and still, we loved each other very much and always have. [We] have always been there for each other. That’s what matters - if you’re there for the person and help [them] along in a relationship, [have] respect for them and what they’re doing and being there for them… [You have to] be together on the other side."

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According to Bartlett Daniels’ book, she began to look for a "kinder and gentler man" in the early years of her marriage with Daniels, now 95. Sometime in 1959, she had "an affair that lasted a few months" with an actor who was "slightly boring." However, "the sex was good."

"I never felt guilty because I never felt tied to fidelity, and neither did Bill," she wrote.

Bonnie Bartlett Daniels and William Daniels embracing

In her new memoir titled "Middle of the Rainbow," Bonnie Bartlett Daniels, right, described how she and William Daniels had an "open marriage" early on in their relationship.  (Robert Isenberg/NBCU Photo Bank)

The fling came and went. In the book, she also described how in the early ‘70s, Daniels’ affair with a female producer in New York left her "devastated." By then, she "could no longer tolerate any kind of open marriage."

It seemed that their relationship was doomed, but the pair weathered the storm as they "grew up."

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"Bill and I have moved forward day-by-day and eventually, the days added up," she wrote. "We’ve been happy together and sad together, and somehow stayed together for seven decades."

Bonnie Bartlett Daniels and William Daniels today

Bonnie Bartlett Daniels and William Daniels, pictured today, are proud parents to two sons. In "Middle of the Rainbow," the actress described a personal tragedy - how her only biological son died during childbirth.  (Getty Images)

Barlett Daniels noted that they have come a long way since they first went on a date while attending Northwestern University.

"Life is all about solving problems," Bartlett Daniels reflected. "We had a very good relationship, [but] Bill was an angry young man, a very angry young man. And that was tough… Bill always said, ‘We had three different marriages. We’ve been together for so long, more than 70 years – a long time. I’m 93, and I met Bill when I was 18, so we had to grow up together."

Daniels has been by the star’s side during some of the most devastating moments of her life. In the memoir, Bartlett Daniels claimed that she was raped by a co-star from the soap opera "Love of Life" in 1957. She does not name the actor in her book, and she shared that he has since passed away.

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Bonnie Bartlett Daniels in Love of Life

Bonnie Bartlett Daniels played Vanessa Raven in the CBS television soap opera, "Love of Life." In her book, the actress alleged she was raped by a costar. (Getty Images)

"I spoke out to my therapist," she recalled. "And he thought I could stop it if I could… I fault him for that… Even my husband didn’t think of it as rape. We didn’t ever use that word for what this guy did. And I hated him. It was a dreadful experience in my life. It made me feel terrible. I couldn’t control it. I wanted to kill him and I couldn’t… I never thought to go to the director of the show. It just never occurred to me that I had the right to speak up… I could have had him arrested.

"I never saw him again until [I was] in Los Angeles, many years later. I went to a party and he was there. Bill and I were there. He walked up to Bill and said, ‘She’s lying. It’s not true. It didn’t happen. She’s been lying to you.’ Bill just said, ‘Move away.’ And I left the party."

Bartlett Daniels praised the #MeToo movement, which has encouraged survivors of sexual assault to openly share their stories and be supported. She also noted that "acting saved my life."

Young Bonnie Bartlett Daniels

A young Bonnie Bartlett Daniels. "Acting saved my life," she told Fox News Digital. (Courtesy of Bonnie Bartlett Daniels)

"So many of us have been through so much," she said. "But now I can tell my own story."

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In her book, Bartlett Daniels also looked back at some of the happier times of her life, such as meeting Marilyn Monroe. The women studied with acting teacher Lee Strasberg. The Hollywood icon passed away in 1962 at age 36.

"She always sat down in the front and she was extremely attentive," said Bartlett Daniels about the blonde bombshell. "It was like she was devouring all of these different scenes that the people were doing and listening to every word that Lee said. She was an amazing student in that way… The Marilyn you knew was all made up, but the [high range] voice was there, the eyes were there, the gorgeous eyes, but without makeup and hair and so on.

Marilyn Monroe at the Actors Studio

Bonnie Bartlett Daniels and Marilyn Monroe, pictured here, studied acting with Lee Strasberg. (Getty Images)

"She had kind of reddish brown hair. When she needed to touch up, you could see all of that. She was interested in learning. She was a real student. And of course, she was fascinated by Lee. He really wanted to make her able to work on stage, which is much harder than what she was doing. And to be able to do really interesting characters… We all liked her."

"She had such a bad background, it was too late to help her really, to live her life, I think," said Bartlett Daniels. "She was a little removed. She had her own bottle of champagne [in Strasberg’s] house, so you wouldn’t touch [it]."

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Bartlett Daniels also found joy in filming "Little House on the Prairie." She played Grace Snider from 1974 until 1979.

Bonnie Bartlett Daniels in Little House

Bonnie Bartlett Daniels played Grace Snider in "Little House on the Prairie." (Photo by NBCU Photo Bank/NBCUniversal via Getty Images via Getty Images)

"[Michael Landon] was a wonderful producer and a wonderful director," she said. "He really gave me a lot of space… He would listen to me. He liked to tease me because… I would make technical mistakes and he would laugh. They thought that was very funny… He really listened to me and it cost time because he did not listen to people. He didn’t let people redirect. And he let me do that once because he really respected me. Tremendous respect from Michael. And I loved all the people on the show. I loved working with them all. It was so much fun. Melissa [Gilbert] was so great, this wonderful child."

Bartlett Daniels also called her time on "St. Elsewhere" a "privilege." She and Daniels played spouses in the ‘80s medical drama, which made them Emmy winners.

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"It was so well-written and produced," she said. "We had so many wonderful actors [in] it. We all knew there was something special about this that we’d probably never experience… again, with all of us together… Bill of course had a major role and my role was small when I went in, but it got a lot bigger. And they wrote for us, which was wonderful… I did suggest a very important storyline, that we could be grandparents… [And] Denzel [Washington] was on his track to becoming a star. He knew that and we all knew it. This was just a job to fill in until he became a movie star."

Bonnie Bartlett Daniels filming a scene in St. Elsewhere

Bonnie Bartlett Daniels, right, made her mark in the medical drama "St. Elsewhere" alongside her husband, William Daniels, left. (David Sutton/NBCU Photo Bank)

Bartlett Daniels did not think twice about trying her hand at comedy. She had a guest role in "Golden Girls" and played Tim Allen’s mom on "Home Improvement."

"[Tim] was so much fun to work with," she said. "I appreciated him so much. He was fun. He taught me about having fun on stage. It was television, but it was a stage and I could have fun. I never had fun. Strasberg never taught fun. Strasberg never knew how to teach fun. And that was a big lack in his teaching. But ‘Home Improvement’ was fun. I can see why [Tim] has gone on and on. Why he’s such a big star."

Bonnie Bartlett Daniels in Home Improvement

Bonnie Bartlett Daniels, left, played Tim Allen's mom on "Home Improvement." (ABC Photo Archives/Disney General Entertainment Content via Getty Images)

Bartlett Daniels’ last credited role was in 2017’s "Better Call Saul." Today, she resides in Southern California with her beloved husband. They are proud parents to two sons, and they spend much of their time with their grandchildren.

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Bonnie Bartlett Daniels with her Emmy

Emmy Winners and real-life husband and wife, William Daniels and Bonnie Bartlett Daniels, celebrate their Emmy Awards backstage at the Emmy Awards Show, Sept. 21, 1986 in Pasadena, California.  (Photo by Bob Riha, Jr./Getty Images)

"I’m writing at such a late age," she chuckled. "Some people may think, ‘Why is she doing this now? She’s so old.’ I guess for a long time I never felt the need at all. But then as I got older, I thought I had some history to tell… Bill and I have been very lucky that things worked out. There’s no magic formula. We’ve just been lucky."

If you or someone you know is suffering from abuse, please contact the National Sexual Assault Hotline at 1-800-656-4673.