William Daniels, 95, best known for playing Mr. Feeny, the most beloved character on 1990s sitcom Boy Meets World, apparently used to have an open relationship with his wife.

Speaking to Fox News Digital, William's wife, Bonnie Bartlett Daniels, 93, revealed she and her husband "never felt tied to fidelity" in the beginning of their 72-year marriage, resulting in an open marriage for many years.

"I guess it was a little bit of an open marriage at first, but that was very painful. That didn’t work well," Bonnie shared.

Bonnie and William got married in 1951.

"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," she continued.

However, Bonnie added it wasn't only painful for her, but "for both of them," calling it "something they both had to go through."

"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," she told Fox News Digital.

The Emmy-winning Little House on the Prairie actress shares details about her iconic marriage in her new memoir, Middle of the Rainbow.

According to her book, in 1959 the actress had a months-long affair with another actor who was "slightly boring." However, "the sex was good," and due to her and William's openness, she never felt guilty about it.

However, by the 1970s, the open marriage had begun to take its toll after William had an affair with a producer in New York that left Bonnie "devastated."

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

Bonnie met William when she was just 18 and he was 20. The pair "had to grow up together."

Over the years, the couple adopted two sons and now spend their days with their grandchildren in California.

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