Dr. Veluvolu and Dr. Gill started looking for a place of their own after their wedding. But once they had crunched the numbers and toured open houses, they realized they couldn’t afford one. “Realistically, we don’t have the down payment to even come close to buying something,” said Dr. Veluvolu, 32, a chief resident at the State University of New York Downstate Medical Center.

And for a one-bedroom rental in the same neighborhood, he said, “we’d have to spend an additional $1,000” a month. So, for now at least, the couple have decided to continue apartment-sharing until they can find something they can afford. Last month, another person joined the mix: Dr. Meyer’s boyfriend.

“If we were living in any other city,” said Dr. Gill, 30, an attending physician at SUNY Downstate, “the situation would not exist: a married couple living with a roommate and his boyfriend. It’s New York City.”

When Dr. Veluvolu and Dr. Gill eventually do move out, Dr. Meyer and his boyfriend plan to take over their space and rent out the spare room. “I guess I’m just keeping up the tradition,” he said.

As with any roommate situation, tact is required in these households.

A few weeks ago, for example, Dr. Veluvolu and Dr. Gill were celebrating their one-year wedding anniversary when Dr. Meyer and his partner came home. “They had a bottle of Champagne and Raj was making dinner for Harj and there were flowers on the table,” Dr. Meyer said. He and his boyfriend quickly retreated to their bedroom and ordered pizza. “We said, ‘Let them have their moment.’ ” And Dr. Gill said she reveled in the time the couple had to themselves when their roommate was on vacation. “It does take away from intimacy,” she said. “When he’s not there it makes a big difference. We can be more like a couple.”

“We can walk around naked more often,” Dr. Veluvolu chimed in.

The way Gregg Anderson and Peter Talley look at it, renting out the spare room in their two-bedroom, one-bath apartment is plain old common sense. “Realistically we could afford to live here by ourselves,” said Mr. Anderson, 46, a corporate meeting planner and freelance interior decorator. But the extra cash they receive each month has allowed them to buy a piece of property in Texas.

“It’s like a part-time job,” he said.

The couple married in 2011 and decided to take on their first roommate nearly three years ago when they moved from a one-bedroom rental in a Hell’s Kitchen luxury building to a two-bedroom on a higher floor. Since then, they have had four roommates, including two who worked at the United Nations and needed a place to stay for several months.