WESTFIELD — Daniel and Patricia Cyr loved having the family over to their lake house on the point, and taking Dan’s handmade wooden pontoon out for a twilight ride.

They loved making their grandkids puzzles, wooden ones shaped like race cars. He would cut the pieces, and she would paint them.

Most of all, through 40 years of marriage that Patricia’s best friend called a “classic love story,” they loved each other.

So when Patricia Cyr saw her husband in distress in the water during a boat ride Monday evening, she dove in after him, even though she could not swim.

By the time rescue came, they had both drowned. Patricia Cyr had tried to reach her husband, her family said, but could not save him, or herself.

“It was the ultimate sacrifice,” said Carol Krause, a neighbor and best friend of Patricia Cyr.

In some heartbreaking way, the way they died honored the life they shared, said Krause and Miranda Landry, the couple’s youngest daughter.

NANCY PALMIERI FOR THE BOSTON GLOBE

Daniel Cyr had jumped in the water after Sadie, a West Highland terrier.

“They died together,” Krause said from the couple’s lakeside home in this city west of Springfield, tears welling in her eyes. “It’s a saving grace.”

“Neither of them could have survived without the other,” said Landry, 35.

Daniel Cyr, an experienced boater and strong swimmer, probably left the boat to retrieve the couple’s dog, a West Highland white terrier named Sadie.

Then something happened urgent enough to make Patricia Cyr leap from the idling boat. The couple’s relatives speculate that Daniel Cyr, who had a traumatic brain injury in a car accident a decade ago, had a stroke or aneurysm.

“For her to jump in the lake, he had to be in distress,” Krause said. Daniel Cyr, who loved animals deeply and regularly volunteered at a nearby zoo, would not have thought twice about going in after the dog, she said.

Landry said her father’s previous injury probably put him at greater risk of sudden trauma.

Just before 6:30 p.m., police received an emergency call about two people drowning. A passing boater brought Patricia Cyr to the dock, but she was unresponsive. Daniel Cyr was found floating face down in the water. Both were taken to the hospital, where they were pronounced dead.

Witnesses told authorities that they saw Daniel Cyr jump into the water after the dog, and that his wife followed when she saw him in trouble and screamed for help, said Jennifer Fitzgerald, assistant district attorney.

The couple had owned dogs throughout their marriage. But when a longtime pet died about a year ago, they thought that might be enough.

“They said they didn’t want to go through it again,” Krause said. “They said it was too hard when they go.”

Yet when Daniel’s sister, a dog breeder in the Lawrence area, offered them a puppy a few weeks ago, they couldn’t say no.

“He loved animals,” Krause said. “He volunteered at the zoo just to be with them.”

Sadie was pulled safely from the water, and yesterday had been returned to the Cyr home. She will live with Cyr’s sister, the family said.

Daniel Cyr served in the Marines during the Vietnam War, Krause said, and ran his own car-repair business. Patricia was a bookkeeper at a bank, she said. Both grew up in Springfield, and met when Cyr returned from Vietnam. In the Marines, he had met Patricia’s brother, and came to live with him while he got on his feet. Patricia, one of 15 children, was living there, too, and before long they were a couple.

They went on to have three children and seven grandchildren, whom they doted on without reservation, Landry said with a sad smile. They often suggested that their children spend a night out on their own, angling for a chance to baby-sit.

Last Wednesday, Landry and her husband took them up on their offer, leaving their two children for a night in Boston to celebrate their anniversary. The kids had a great time, she said, and not just because they got to eat ice cream and Twinkies.

Landry said her parents spent a happy life together, and their marriage set a strong example.

“They were just the best role models for relationships,” she said. “They were so proud we all settled down with good mates and raised families.”

Fighting back tears, Landry said her parents worked hard to “raise us right.”

“Their jobs are done now,” she said. “They left us everything we need.”

Daniel Cyr loved NASCAR racing, especially Dale Earnhardt. His wife watched the races by his side, Krause said.

“You didn’t bother Danny on a Sunday afternoon,” she said. “He loved his races.”

She often accompanied the family on weekend camping trips that featured cookouts, dominoes, beers by the fire, and lots of stories. Often old ones, she said, but embellished over time.

Landry said her parents were “just good people,” and that her mother’s attempt to save her father was in keeping with their devotion to each other. “That’s just what she would do,” she said.

As she spoke, Sadie came running up to her, and she scooped her up and held her close. “Why couldn’t you just stay on the boat?” she said, trying to laugh.

She said she was not angry at the dog, and did not blame it. But the dog was not going to stay with them, she said.

“I won’t have any interest in seeing the dog,” she said. “I don’t think my kids could handle it, and we need to move on.”