It seemed a given they would have only two children. “You get into this stage at life where you kind of map things out,” Mr. Ruben said. “You ask, will we have enough for the kids to go to college and the rest of it? You do a lot of calculations that bring home the enormity of having a third child.”

At the time, Ms. Bakoulis had just turned 40 and intended to come back strong as a master runner for her new decade. “I had a really good year and a half — and then had an overwhelming urge to have a baby. It came out of the blue and it was my idea,” she said.

Still, Mr. Ruben didn’t quite think it was going to happen, he said. “But then she was like, guess what? It was fait accompli.”

And once she was pregnant, he was totally on board. “Flesh and blood is different from calculations,” he said.

The scariest patch in the marriage came the night of their youngest son’s birth. After Danny was born, Mr. Ruben left the hospital. At 1 a.m. the hospital called, asking him to return immediately.

Ms. Bakoulis was bleeding. “It was something women might have died from only a few years ago,” he said. He was terrified and felt helpless. All he could do was “watch the doctors going back and forth in the operating room — going out and then going back in again.”

She had an emergency hysterectomy and spent the next 24 hours in the intensive care unit. Nine days later, she was home. Mother and child were fine. And Mr. Ruben embraces the “completeness and rightness of the whole family.”

Since then their course has been smooth, until now. They disagree over the possibility of moving.

He wants to stay in their mortgage-free Upper West Side apartment, where they have lived for 16 years. “I like things the way they are,” he said. “We put a lot of work into the apartment, and it’s kind of comfortable.”

He is not on board with his wife’s dream of moving to a less expensive place in Harlem. “My view is, we’re pretty comfortable financially,” he said. “We’re not going to run out of money anytime soon.”

Mr. Ruben kind of feels it’s his turn to win one.

“It’s not settled,” Ms. Bakoulis admitted, even as she continues to hunt for a new and cheaper dream house. “But if there’s one thing I know, if you can know anything for certain in life, is that Alan and I are going to grow old and die together. He will be my friend, lover and companion for the rest of our lives.”