Barbara Bushkin attended a fundraiser Sunday at a District nonprofit organization, then got into her car that evening to return home to Fairfax County.

She crossed the Potomac River and pulled off the George Washington Parkway, into the Theodore Roosevelt Island parking lot. Bushkin, 72, sent text messages to friends and family members while posting to social media.

Her husband and his caregiver were waiting for her, but she never came home.

Arthur Bushkin called police to report his wife missing and asked on social media whether anyone had seen her. On Monday, her body was found in the river — still strapped in the driver’s seat of the black SUV.

“I don’t know that it’s completely hit me yet,” Arthur Bushkin, 75, said Tuesday.

He wondered whether his wife stopped at the parking lot because she wasn’t feel well. He said she could have fallen asleep, passed out or suffered a medical incident before her SUV went into the river. An autopsy is pending; D.C. police were continuing to investigate.

Arthur Bushkin said his wife hadn’t been feeling well for about two months. She was often tired and wasn’t “her perky self,” he said.

Earlier Sunday, she was falling asleep at their home and her husband suggested she take a nap. That evening when she attended a fundraiser at Martha’s Table — a District organization to which she and her husband had donated over the years — nothing appeared amiss, friends later told him.

At the fundraiser, she asked questions, chatted and posed for a picture before getting into her Lexus SUV and heading home, Arthur Bushkin said.

He said police told him that, based on text messages and calls, she left Martha’s Table about 7:50 p.m. and was in the parking lot at Roosevelt Island for about 1½ hours.

She left a message for her son in Los Angeles, posted to Facebook and wished friends a happy birthday. Then she texted her husband that she was fine and she missed him.

“It was nothing unusual,” Arthur Bushkin recalled.

On Monday morning, he realized that his wife hadn’t come home, and reported her missing. Fairfax County police tweeted she was “endangered due to mental and/or physical issues.”

A caller to police reported seeing a vehicle go into the river Sunday night near Roosevelt Island, but Arthur Bushkin said there was no evidence at the time to think it was her SUV.

Rescuers searched the river for hours and found the SUV and her body Monday evening about 500 feet from where it entered the river. Arthur Bushkin said in a Facebook post that a car was seen “rolling down the bank from the parking lot into the Potomac River, where it quickly submerged.” He continued: “This appears to be a tragic accident, quite probably related to some medical event.”

Kim R. Ford, president and chief executive of Martha’s Table, said in a statement that the organization was saddened to hear of Barbara Bushkin’s death, calling her a “fierce supporter and advocate” of the group’s work. She “was her warm, vibrant self” during Sunday’s fundraising meeting, Ford recalled.

Julie Silverbrook, 31, of Bethesda said she got to know the Bushkins through helping at Martha’s Table about five years ago. She described Barbara Bushkin as “one of the kindest, loving, giving people you’d ever meet.”

The Bushkins met nearly 60 years ago.

They were high school sweethearts in Chicago, lost touch for decades, married other people, raised kids and had careers before reconnecting nine years ago. They spent seven years writing a book about their love story.

“Lifelong Valentines: An Inspirational True Story of Love, Perseverance, and Resilience” was published in February. It’s described on Amazon as “a true story of friendship and love, perseverance and resilience, that lasted a lifetime.”

In the book, the Bushkins wrote of how they met in the fall of 1960 when he was 17 and she was 14, became best friends and then went on to live separate lives. She went to college at the University of Wisconsin, got married and worked as a teacher and real estate agent in La Jolla, Calif., where she lived for three decades. He went to the Massachusetts Institute of Technology and later worked in Washington in the Carter administration, then became a telecom executive before running a technology foundation.

Over the years, both suffered health problems. She was in a traffic accident at age 19, a bike crash that left her with a concussion, and also had breast cancer and underwent knee surgeries. He had heart troubles and two back surgeries that made walking difficult.

In the book, Barbara Bushkin recalled seeing him at a volleyball court and thinking, “I’m going to beat him, and I’m going to meet him.” She did and the two dated. Even though they lost touch after college, Arthur Bushkin said he never forgot her.

He tried to find her online but was unsuccessful until November 2010 when he came across a blog post on a 1950s summer camp where someone asked about Barbara. Another person responded that she was in a cancer survivor group. He tried emailing women with similar names, explaining how he’d “love to reconnect and learn how you are.”

One night he got a call.

The woman asked, “Are you still awake?”

Yes, he answered. “Who’s this?”

She responded, “Barbara.”

They talked for 2½ hours. They dated, commuting between Washington and California. Eventually, she sold her California home and moved to Vienna. On Oct. 9, 2011, surrounded by friends and family in their living room, they got married.

In their book, they wrote, “We realized what had always been true: the friendship we had, and still have, was and is true love.”

A picture of the couple in the book shows them smiling in front of a birthday cake with “Never give up on love” written above the photo.

Arthur Bushkin said the couple had agreed years ago to be cremated. Someday, their ashes are to be combined in an urn.

“We had a couple of bumps in life,” he said, noting they were “not the best physical specimens.”

But still, they remained optimistic.

“We generally didn’t look in the rearview mirrors of life,” he said. “We’ve survived so many things and I’m a lucky guy.

“I knew Barbara.”

Magda Jean-Louis, Peter Hermann and Martin Weil contributed to this report.