By the time Nancy Reagan sat down with Mike Wallace of “60 Minutes” in 2002, her eyes had lost their familiar gleam.

More than a decade out of the world spotlight, hers was now a life consumed by a torturous, private struggle. Her husband’s generous spirit — once among the most commanding on Earth — had been reduced by Alzheimer’s to a passing flicker of semi-cognizance.

In the White House, she’d developed a reputation as a fierce protector of the president, even while surrounded by allies. Now the former first lady, who had decades earlier said that her life didn’t begin until she met Ronald Reagan, was still protecting the love of her life.

Nancy Reagan died Sunday, March 6 in Los Angeles. She was 94. (Monica Akhtar/The Washington Post)

This time, however, she was doing it on her own.

“It really is the long, long goodbye,” she told Wallace of caring for someone with Alzheimer’s disease.

“When you come right down to it, you’re in it alone, and there’s nothing that anybody can do for you,” she added, her stoic eyes turning watery. “So it’s lonely.”

Only months before the interview, Wallace noted, the Reagans had marked their 50th wedding anniversary.

What should have been a day of celebration, Reagan told Wallace, was far more complicated for her. The hardest part, she said, was not being able to share decades of memories together.

“How I’d love to be able to talk to him about it,” she said. “There were times when I had to catch myself, because I’d reach out and start to say, ‘Honey, remember when …'”

“Do you think he knows you still?” Wallace asked.

“I don’t know,” Reagan responded.

As her husband slowly slipped away, Reagan’s daughter, Patti Davis, reconnected with her mother, Wallace reported. As her parents’ struggle deepened, Davis wrote poignantly about the effect the disease was having on each of them in their own way.

She measured the depth of that struggle, Wallace noted, by looking into her parents’ eyes.

“In the early stages of Alzheimer’s, the eyes have a weariness, a veil of fear,” Davis wrote, according to CBS News. “I used to see my father’s eyes simultaneously plead and hold firm. Slowly, sometimes over months, sometimes over years, the eyes stop pleading. … A resignation, an acceptance of distance, strangeness, a life far from home. You know the look when you see it. And the only mercy is that the fear seems to have subsided.”

Wallace read the passage to Nancy Reagan out loud.

“It’s true, it’s true,” she said. “A whole different look in eyes. Whole different look.”

Wallace noted that Davis had some somber observations about her mother’s eyes as well. The long goodbye, she’d noticed, was taking a toll.

“My mother’s eyes are frequently such deep wells that I have to look away,” Wallace quoted Davis as writing.

“I think she means that when she looks at me, she sees a deep sadness,” Nancy Reagan replied.

Reagan told Wallace that she wasn’t sure whether her husband still knew who she was. She found comfort in remembering their past and by reading letters she’d saved from their time together, letters that captured the intensity of their bond.

One missive — written by President Reagan aboard Air Force One and cited by Wallace — laid bare the president’s attachment to his wife: “When you aren’t there I’m no place, just lost in time and space. I more than love you, I’m not whole without you.”

Wallace asked whether, given her husband’s poor condition, she was ready to say goodbye.

“No,” Reagan said firmly. “Not really. He’s there. He’s there.”

That same year, she published “I Love You, Ronnie,” a poignant collection of the couple’s love letters. In the book, she wrote even more about coping with her husband’s illness. Ronald Reagan died two years later, in 2004.

“We’ve had an extraordinary life … but the other side of the coin is that it makes it harder,” she wrote.

“There are so many memories that I can no longer share, which makes it very difficult. When it comes right down to it, you’re in it alone. Each day is different, and you get up, put one foot in front of the other, and go — and love, just love.”

This post has been updated.