CHICAGO (CBS) — More than 1,500 websites now offer the promise of love at the click of a mouse.

Online dating has blossomed into a $2.1 billion industry, and it’s expected to grow another 7 percent by the end of this year. But as CBS 2’s Susan Carlson reports, despite the staggering popularity of online dating a new review of research points to some problems.

Lisa Watson says she and her husband, Neal, dated for nine months before they decided to get married. They met on eHarmony, which claims that 542 people get married every day as a result of their website.

Lisa Watson said the service asks you “1,010 questions, which is OK.”

eHarmony claims to use a scientific method, an “algorithm,” that matches couples up based on their personalities, values and interests.

But Eli Finkel, an associate professor of psychology at Northwestern University, is skeptical.

“We reviewed 80 years of relationship science, and we’re pessimistic that the algorithms can be effective,” he says.

“They’re way over-selling,” Finkel says. “They’re promising you the moon, and what they can deliver is almost no better than random.” boasts 1.6 million paid subscribers, a 12 percent increase from a year ago. It changes its algorithm almost weekly in response to what people click on.  For example, if you always click on blondes, the website will start showing you more blondes, says Amarnath Thombre, senior vice president of strategy for

Finkel insists that has nothing to do with determining whether two people will have chemistry.

Here’s another potential problem: Some websites don’t just show you a handful of profiles, they give you access to hundreds or even thousands of them.  With so many choices, some online daters may be less likely to commit.

“It tends to get people in a more shopping mentality than they otherwise would be in, and they tend be a little bit less likely to say, ‘Yeah this person’s great, and I’m not going to look for another person,’” Finkel says.

The happily-ever-after stories don’t always come easily.

“I probably went on like 50 dates. Most of them were not second dates – very few, maybe five or six,” Lisa Watson says.

Despite the pitfalls, Finkel still insists online dating is good because it introduces you to people you otherwise wouldn’t meet.

In response to this report, eHarmony issued a statement. Here it is, unedited:

“On average, 542 people marry every day in the U.S. as a result of being matched on eHarmony, according to a 2009 study conducted for eHarmony by Harris Interactive. That is nearly 5% of new marriages in the U.S.  eHarmony¹s matching system is based on years of empirical and clinical research on married couples. As part of this work we have studied what aspects of personality, values, and interest, and how pairs match on them,  that are most predictive of relationship satisfaction. We have used that knowledge to build eHarmony¹s matching algorithms.”