The difference was small, although the number of people who met online was big, and researchers who study marriage say the study has some weaknesses. Still, lead author John Cacioppo, of the University of Chicago, said it should give comfort to anyone who fears that meeting online isn't the best way to begin a romantic relationship.
"I hope this encourages people to feel authentic and not odd if they feel so busy that they're going online to meet people," said Cacioppo, director of the university's Center for Cognitive and Social Neuroscience. "It's a new environment and a new world, and it's not one we should be afraid of."
In the new study, eHarmony, an online dating service, commissioned Harris Interactive to conduct an online survey of more than 19,000 people in the United States who were married to members of the opposite sex between 2005 and 2012. Independent statisticians verified the results of the survey.
Since the marriages were so recent, the rates of divorce (5 percent) and separation (2.5 percent) were low.
The researchers found that more than a third of those surveyed met their spouses online. Of those, 45 percent met through dating sites, while 21 percent met through social networks like Facebook.
Those who met offline were more likely to be very old, very young and not wealthy; they also were most likely to meet each other at work (22 percent), through friends (19 percent) or at school (11 percent).
The researchers found that 7.6 percent of those who met offline had gotten divorced, compared to 5.9 percent of those who met online. This difference held up even when researchers adjusted their statistics to account for high or low numbers of people who shared similarities like age or income.
The study also found that those who met online were slightly happier in their marriages. Their spouses, however, didn't get a say in the survey, and the study doesn't provide a layperson-friendly way to understand the differences in how happy the marriages seemed to be.
Why might marriages that had their start online be happier and more stable? One possibility is that they're more focused on finding relationships "rather than falling into a relationship with someone they met through a friend or at work," said Elizabeth Schoenfeld, a graduate student at the University of Texas who studies human behavior. "It is possible that this initial motivation to secure a relationship partner may translate into a later motivation to stay in the relationship."
Markie Blumer, an assistant professor at the University of Nevada, Las Vegas, who studies marriage, said the study is "pretty solid," although it has some flaws.
For one, she said, it's an online survey that would naturally include people who are especially Internet-savvy. For another, it ignores same-sex couples, which are even more likely to meet online, she said.
Future research, Blumer suggested, should take a closer look at how relationships evolve with or without technology. It's possible, for example, that some people meet online but then develop their romance in person.