The key ring is the new wedding ring.

It used to be that you fell in love, got married, and then bought a home together. Now, many people are skipping the marriage part -- and going right to buying a home together. The number of non-married people who got mortgages together rose from 20% last year to 22% this year, according to data on single-family homes released Thursday from real estate research firm ATTOM Data Solutions.

Many of these unmarried co-borrowers are parents co-buying with their children, but there is also a significant contingent of unmarried couples who buy a home together, says Daren Blomquist, senior vice president at ATTOM Data Solutions. “There are fewer married people -- and so more couples are buying without being married.”

Indeed, only about two million marriages happen each year nowadays -- that’s down by roughly half a million from the early 1980s, according to Census Bureau data. What’s more, the share of American adults who have never been married is at a record high (20%) with young adults leading the pack, according to the Pew Research Center.

Many of these unmarried couples buy with their partners because they couldn’t afford to buy the homes on their own, says Blomquist. Indeed, the cities with the highest share of unmarried co-borrowers tend to have pricey real estate markets.

5 cities with the highest percentages of unmarried co-borrowers 1. Miami (40.2%) 2. Seattle (37.4%) 3. San Diego (28.9%) 4. Los Angeles (28.2%) 5. Portland (27.7%).

Buying before marriage doesn’t mean you’ll never get married: A 2013 survey from real estate firm Coldwell Banker found that 17% of all married adults had purchased their home with their current spouse before they were married. People in the South are more likely than those in the Northeast to have been married before they bought their home, the data showed.

But for many unmarried couples, staying un-hitched -- even if they own a home together -- is how they like it. Nearly four in 10 Americans (39%) say that marriage has become an obsolete institution for Americans. And fully 5% of Americans who have never been married say they never want to get married, Gallup data shows.