1 of 2
©istockphoto.com/eyecrave
People aren't just getting married at lower rates. Being in a committed relationship at all is on the decline.

It's well known that millennials are the most unmarried generation in American history, but a new report by Gallup suggests that tying the knot isn't the only union youngsters are avoiding.

In fact, there's been little to no growth over the past decade in those who identify as "living with partner," according to Gallup. While only 16 percent of 18- to 29-year-olds are currently married, only 14 percent of that same demographic say they are living with their partner. The highest that percentage has been in the past 10 years is 15 percent.

The same can't be said for those ages 30 to 39. According to Gallup, a much larger chunk of that age demographic is currently married (56 percent). Only 19 percent have never been married, and only 13 percent live unmarried with a partner.

In short, millennials are shaping up not only to be the unmarried generation, but a generation of singles.

As Vox's Margarita Noriega points out, even though the 30 to 39 demographic is married at a much higher rate than younger Americans, you can see the trend away from nuptials in that older generation. Millennials appear to be simply carrying the trend forward.

Read more: U.S. marriage rate hits new low and may continue to decline

But the fact that millennials aren't replacing marriage with similar but less legally committed relationships may actually shed further insight into why millennials are opting out of marriage in the first place. As Herb Scribner of Deseret News National pointed out last October, economics has a lot to do with why marriage has fallen out of favor, and that's a problem that isn't easily solved by choosing to live together.

"The decline of marriage is parallel to the decline of America’s economy," Scribner wrote, citing Trevor Butterworth's article in Forbes on why pragmatism has kept millennials from marrying.

"Marriage rates fell even more drastically during the Great Recession, when young adults had a tough time landing their first jobs and other Americans found themselves collecting unemployment checks," CNN Money's Tami Luhby wrote last year. Though Luhby argues that certain demographics may see a rebound in marriage rates later in life (mainly, educated whites), the recession's long-tail effects will likely carry on for a while.

In fact, new forecasts by Demographic Intelligence predict that marriage rates in 2016 are expected to hit historic lows.

"Millennials are such a big generation, we’re going to have more people of prime marriage age in the next five years than we’ve had at any time in U.S. history. For that alone, we’d expect an uptick in marriage rates,” Sam Sturgeon, president of Demographic Intelligence, told The Washington Post. “That’s not happening.”

The Washington Post's Brigid Schulte, in his article about the DI forecast, cites three prominent reasons why millennials are choosing to remain single, economics prime among them.

That might also be why young singles aren't replacing marriage with live-in partners. It's not the idea of marriage per se that people are turning away from. In fact, a Gallup poll from 2013 found that the majority of millennials who aren't married do want to settle down one day. The fact that it's money that deters them means that living in non-committal relationships under similar economic stresses probably doesn't sound too appealing.

Related links:

Here’s how long marriages last across the world

Where you live impacts whether you'll marry by 26

The easy mistake that could destroy your relationship

JJ Feinauer is a writer for Deseret News National. Email: jfeinauer@deseretdigital.com, Twitter: jjfeinauer.