For their 40th anniversary this month, Marlo Thomas and Phil Donahue might have been traveling, including to San Francisco, to promote their new book, “What Makes a Marriage Last,” which features in-depth conversations with 40 other celebrity couples about how they’ve stayed together.

Phil Donahue and Marlo Thomas at their wedding in 1980 (Courtesy of Phil Donahue and Marlo Thomas) 

Instead, the icons of media and progressive politics have been stuck at home like the rest of us, sheltering in place due to the COVID-19 pandemic. For Thomas and Donahue, that means rarely leaving their Manhattan apartment, a situation they say has brought new insights to their famous bond.

“It gives a chance to look at your dynamic with your spouse,” Thomas said. “When you’re in the same place all the time, for, like two months, you notice more things about your spouse you wouldn’t notice as much if you were busy, rushing around with your usual life.”

While not a how-to book, “What Makes a Marriage Last” takes a incisive look at an institution that ends in divorce for an estimated 39 percent of American couples. The couples who shared marital challenges and survival strategies with Thomas and Donahue include Jimmy and Rosalynn Carter, Chesley “Sully” and Lorrie Sullenberger, Elton John and David Furnish, Jamie Lee Curtis and Christopher Guest, Chip and Joanna Gaines and Kelly Ripa and Mark Consuelos.

Thomas and Donahue married in 1980, three years after he interviewed her for his eponymous day-time talk show. “It was a spontaneous, chemical reaction,” Thomas said.

Thomas became one of America’s best known feminists after producing and starring in “That Girl,” the sitcom that introduced the independent career woman to TV screens. Donahue’s talk show also became a cultural force by introducing the town-hall format that would later become Oprah Winfrey’s hallmark. He also gave his mostly female audience, post-“Feminist Mystique” housewives, a chance to learn about major issues of the day by hearing from writers, politicians, activists and other newsmakers

Notably, Donahue’s 1974 interview with Equal Rights Amendment opponent Phyllis Schlafly makes a cameo appearance in the new Hulu series “Mrs. America.” He said he hasn’t seen the show. Thomas’ work with the Ms. Foundation as well as her book “Free to Be You and Me,” also were featured in “Mrs. America.”

Thomas and Donahue had never worked together before. But they felt compelled to collaborate on “What Makes a Marriage Last” after friends shocked them by announcing they were divorcing after 28 years together. They pondered why some couples stay together and whether they still had things to learn about their own relationship, which they reveal in this conversation.

Q: What are some of the common themes about successful marriage that emerged from your interviews?

THOMAS: Everybody really wanted their marriage to work. They weren’t looking for an escape route. They faced many different challenges: alcoholism, illnesses, unfaithfulness. Kyra Sedgwick and Kevin Bacon lost 30 years of savings to Bernie Madoff. … But instead of blaming each other, or being afraid they couldn’t handle it — which is why a lot of people run away from confrontation — they stuck with it.

DONAHUE: Who said it was harder to break up than to stay together?

THOMAS: Elsa Walsh, who is married to Bob Woodward, said she doesn’t understand “the impetus for disruption” — all the energy put into breaking up.

Q: In her introduction to the book, Marlo writes about the small, day-to-day ways you two connect. Why are those things important for couples?

THOMAS: It is part of your history, part of your own code that you don’t have with anyone else. Peter Hermann, Mariska Hargitay’s husband, also said that sometimes people go into marriage expecting the other person to make them happy. That will never work. I’ve known people who’ve had five marriages, and each time, they’ll say, that person didn’t make them happy, so they move onto the next person.

DONAHUE: I had (band leader) Artie Shaw on my program. A woman in my audience asked him, “Mr. Shaw, why have you been married so many times?” And he said, “I’ll walk into a crowded room and head straight to the woman who will make me the most miserable.”

THOMAS: The funny thing is that we now know, he was just miserable. As Rob Reiner said, “You’ve got to work your side of the street.” You also really have to accommodate the differences between you. Phil is a very laid-back guy and he used to annoy me that he didn’t jump out of the chair as soon as I got excited about something.

DONAHUE: I also learned about jealousy, how draining it can be. It all came home to me when we interviewed Kelly Ripa and Mark Consuelos. He told how (early in their marriage) he was making a movie in Boston, and he couldn’t get ahold of Kelly all day. When he finally reached her, she said “I’m cleaning the toilets.” He secretly got on an airplane, flew to New York and went to their apartment. She opened the door, with a mop in her hand. But he rushed past her expecting to find this tall, dark stranger hiding behind the drapes, or wherever his mind had taken him.

THOMAS: Phil used to be very jealous.

DONAHUE: Marlo made a movie with Kris Kristofferson, and they had a love scene that lasted about five and a half hours. I’m glad that’s behind me.

Q: Are they other couples’ stories that really made an impression?

THOMAS: Many shared the idea that most people go into marriage and don’t know what to expect. Viola Davis said she thought marriage would be 50/50, but it’s 100/100. You’ve got to give it your all. We also were impressed by how many people were in couples’ therapy. Bryan Cranston and his wife said they weren’t looking for a referee, they were looking for an interpreter. Sometimes Phil will say something, and I’ll think, “Wow, that’s pretty harsh.” But we’ve been married long enough to know you don’t start reacting too fast. You would think after 40 years, you would know exactly what your spouse is thinking. But you still need to communicate, so you don’t go off pouting and holding onto the anger.

DONAHUE: James Carville said that when you find yourselves going around and around on what’s a very Micky Mouse issue, that it’s good to say, “Let’s kick this can down the road.”

Q: I also liked the lesson Jamie Lee Curtis said she learned from being in recovery — that you just say, “Stay on the bus, the scenery will change.”

THOMAS: What she meant is that what you’re mad about today, will be gone tomorrow. I love what Melissa McCarthy’s husband Ben Falcone also said about how he goes to bed purposely pisssed because he know it will be gone in the morning.

Q: Isn’t that the opposite thing that we’ve always been told, about how you should never go to bed angry?

THOMAS: All of our couples, except for President Carter and Rosalynn, said they don’t have any desire to stay up arguing. Because, unless it’s something really horrible, they know what they were mad about will be gone in the morning.

Q: Didn’t Jamie Lee Curtis also say that hatred was a component of marriage?

THOMAS: That was a little strong for me. I don’t think I’ve ever hated Phil. I’ve been mad as hell at him.

Q: Any final thing you’d like to share?

THOMAS: Marriage is really worthy it, and it gets better. Always tell the truth about what you’re feeling, and give each other the benefit of the doubt. Viola Davis also said, “Your marriage doesn’t begin the day you walk down the aisle. The marriage begins the day you look over the breakfast table, and something he’s doing really drives you crazy. You think, you’ll never be able to stand it. But I have to stand it because I love this man.”