“We were both old enough to know what was important,” Mr. Nelson said.
Marriage never seemed necessary to the couple over their first 18 years together. They toyed with the idea off and on, but neither bit.
“We always said, ‘If you want to, I’d be happy to,’” Mr. Nelson said. “Judy said to me, ‘I’d follow you anywhere.’ That’s pretty amazing.”
That was enough of a commitment until Mr. Nelson had a serious complication from a burst appendix. Because they were not married, Ms. Collins was locked out of medical decisions.
“I’m a hippie, I don’t get it,” Ms. Collins recalled. “And then I thought, wait a minute, what am I supposed to do? I went into his hospital room with a big frown on my face and said, ‘I think we should get married.’ In my fog, I’m thinking if you’re married, all of those things are simple.”
They were married on April 16, 1996, at St. John the Divine in New York in front of 280 guests, 18 years to the day after they met. Guests included Peter Yarrow, Gloria Steinem, Bill Moyers, Susan Cheever and Donna E. Shalala.
Pondering their four decades together, Ms. Collins said: “You share the good things, share the tragedies, share the traumas.”
“We shared the worst thing that could possibly ever happen,” Mr. Nelson said.
That was the death of Ms. Collins’s son, Clark C. Taylor (his father was Ms. Collins’s first husband), who committed suicide in 1992.
“And we got through that,” Ms. Collins said. “I understand that a lot of people who come up against a tragedy like that don’t necessarily make it through, they don’t necessarily survive it.”
They have survived bouts of jealousy too. Fifty years ago, Ms. Collins and Stephen Stills of Buffalo Springfield and Crosby, Stills, Nash & Young became romantically involved while making an album together. Their time together inspired Mr. Stills’s hit song “Sweet Judy Blue Eyes.” The two remained friends and even toured together in 2017; they’re hitting the road again on May 1.
Ms. Collins has no problem being on tour with a former lover. But in the words of her husband, “it’s a rub.”
“It’s annoying,” Mr. Nelson said. “But the thing is, I can say that.”
He came to a second conclusion too: “I guess I won.”
Leading separate professional lives has also, they believe, helped their longevity. Ms. Collins and Mr. Nelson do not collaborate — they even keep their bank accounts separate — but they do lean on each other for input. He comes to her shows and provides feedback, and she reads his writing projects. (He is probably best known for designing the Korean War Veterans Memorial mural in Washington.)
“It means we help each other but we’re very clear about what we’re responsible for,” Mr. Nelson said.
They are also not shy about asking for help. Once, Ms. Collins suggested they split up. Mr. Nelson said, “Absolutely not, let’s go see somebody.”
“If you have an issue, get someone to help you deal with it,” Ms. Collins said. “Don’t be afraid to talk about it with the person. We both have good relationships with friends that we can run things by. I think that’s also important, that you have an integrated life but you’re not completely, emotionally dependent on one person to be solving everything you have.”
So after 18 years together, was being married any different?
“After we were married, I never had this feeling before, but all of the sudden I didn’t feel alone anymore,” Mr. Nelson said.
“Things go on in your psyche that have to do with the nature of living on the planet and having certain things that are reliable and certain things that aren’t,” Ms. Collins said. “I didn’t have the same kind of feeling during my first marriage when I was young, at all. It was very sustaining and very palpable. But it does make a difference, and it’s a different feeling.”
Mr. Nelson turned slightly to face Ms. Collins, his face relaxed and wide.
“I don’t think you ever told me that,” Mr. Nelson said. “But I agree with you, it is different.”