William Daniels and Bonnie Bartlett Daniels never expected to be married for seventy-three years, especially after having a brief open marriage early in their relationship.

Bonnie previously discussed having an open marriage with the Boy Meets World star in her 2023 memoir, Middle of the Rainbow. In a joint interview with William, 97, for PEOPLE, she reflects on that time in her life and discusses how the longtime pair finally got through it.

“That was a period in New York when everything was open.” Everything was open. We never discussed it. “It just happened,” Bonnie, 95, claims. “We accepted for a while that that could happen.”

The St. Elsewhere star continues, “An extended period of separation is not good for any marriage.” “We didn’t think we’d make it, but we did.”

Bonnie observes that the couple has been “fortunate” thus far, especially because “anything that ever happened was minimal” or “unimportant.”

Bonnie believes that “being respectful” is the finest marital advice she can give others. William also feels that “mutual respect” is essential, and Bonnie adds that “listening to the other person and caring about the other person’s happiness” is required for a long-term marriage.

“I care about your happiness. It’s crucial to maintain your own happiness while simultaneously fostering the happiness of others. Be patient if you’re having a problem; be compassionate and help,” she says. “In college, I helped him become a better student, and he turned out to be an excellent student. He’s helped me.” I’ve had years of pain, migraines, and so on, and he’s always helped me with it, keeping me out of the way while I was sick.” He was quite helpful.

Bonnie, on the other hand, considers their “wonderful” sons, Michael and Robert, to be “the best thing in our marriage” along with their grandkids. “That is the best thing that has ever happened to us.” This occurred following the loss of a child, a period of intense grief and sadness, and the arrival of our two amazing boys, who have brought us immense joy throughout our marriage. “I cannot imagine life without them,” she adds.

Williams believes the pair also got “lucky” in love as they celebrated their 73rd wedding anniversary on Sunday, June 30.

“We never had a problem working against each other because of our different careers,” the author of There I Go Again adds. “The other was happy about whatever happened for the best.” They needed not to harbor jealousy or any other negative emotions. We got along quite well.

William praises his longstanding love, stating, “She is a very competent woman.” She’s brilliant, and I delegate a lot of responsibilities to her.”

“She’s kind of in charge of all the business, all the money, all of that,” according to him. “She takes care of that.”

After all these years, Bonnie says she will “never stop being surprised” by her 73-year-old husband.

“Now and then, he does something that makes me wonder, ‘Where did that come from?’ “Where did it come from?” she says. “Or he does the same with me,” she remarks. “We never stop being surprised by what somebody does.”