What have 20 years of online dating done to Americans' love lives?

Nervous about Valentine's Day? Try a tiger roll.

First dates at a sushi restaurant are 1.7 times more likely to lead to a second, says Match.com, America's largest online dating site. The sushi tip is just one finding from the sixth annual Singles in America survey, which asked 5,500 respondents everything from which politician they want to vote for to which politician they'd be up for dating (Joe Biden and Marco Rubio dominate with 21 percent and 20 percent, respectively). Match's match-making masterminds conclude that it's probably okay to talk religion, politics and money on Date 1, but keep your hands off your phone. And if you're male, double-check those text messages: women are way less forgiving of spelling and grammar errors. 

But even as more and more Americans turn to online dating, as it loses the "desperate" reputation of its early days, the jury's still out on what, exactly, it's doing to singles' hearts and minds. At a time when more Americans are unmarried than ever before, are Tinder and OKCupid changing what Americans want in a partner, or just how they find them?

In 1995, when Match.com began the online dating scene, finding a partner online was something you might keep to yourself. Even in 2005, 29 percent of Americans called it "desperate;" by 2013, that was down to 21 percent. Today, nearly 60 million people use dating sites and apps owned by the Match Group alone, home to sites like OKCupid, Tinder, and Match.com, around 40 percent of those who are single and looking. 

Yet we're a pretty single nation: more adults are unmarried than married, in fact. But one of the biggest debates is whether it will stay that way: are youngish people just delaying marriage, or avoiding it altogether?

Part of the popularity of dating apps may come from the average age of first marriage, which has climbed up 7 years for both genders since 1960: now age 27 for women, and 29 for men. 53 percent of those who have never been married say they'd like to, according to the Pew Research Center, down from 61 percent just since 2010.

And even if they are aiming to get married, fewer singles care if their neighbors do. Two-thirds of people between 18 and 29 told Pew that "society is just as well off if people have priorities other than marriage and children."

The multitude of online dating critics often suggest that websites' endless array of potential dates helps create a non-committal culture, where even small differences don't seem worth working out, since the next partner could be just a click away, and that Tinder & Co. have brought out the worst in so-called "delayed adolescence," the stretch of singlehood many people in their 20s are enjoying, or at least enduring, far longer than their parents or grandparents did. And there may be evidence that, for better or worse, single people do move on to new relationships faster than they used to. 

But others say the alarm about "singles nation" is overblown, or that the changing landscape of American marriages have far more to do with long-term societal changes than a couple of phone apps. The vast majority of college-educated women, for example, are expected to get hitched at some point — one of the demographics most familiar with online dating, whether through their own experiences or their friends'. Millennials actually report having fewer sexual partners than Generation X-ers, and 59 percent of men told Match that they believe in love at first sight. (Women were slightly more skeptical: just 49 percent.)

There are a slew of reasons why Americans may be more accepting of eternal singlehood, or just delayed marriage, including contraception and women's increased independence as educational and economic opportunities improve. But a significant number of singles aren't thrilled about it, and one third of unmarried Americans between 25 and 34 say financial insecurity is holding them back from marriage.

"We have two different family systems in the US," Johns Hopkins University sociology professor Andrew Cherlin told The Christian Science Monitor last June, referring to a "marriage gap" between economic haves- and have-nots: better-educated and higher-paid Americans tend to marry each other, and stay married, at higher rates, stability they tend to pass on to their children. Those who decry "delayed adolescence" may want reroute some of the blame from swipe- and match-dating culture to the bigger economic picture.

In the meantime, a bit more advice for Valentine's Day: Gentlemen, if you haven't answered her texts for a week, Match says you've missed your chance.