As Valentine's Day looms over the horizon, two online dating sites have struck up a romance--with each other.

IAC's online dating branch, Match.com, has bought OkCupid for $50 million in cash.

While the 16-year-old Match.com has about 1.8 million subscribers, OkCupid is a free site that generates its primary revenue from advertising. OkCupid is just one of a few sites that Match.com has snatched up, though certainly the most high-profile. Match.com also purchased People Media and Singlesnet in the past few years.

Launched in 2004, OkCupid also runs a blog called OkTrends analyzing the data on the site that draws about a million people monthly.

"OkCupid has been a real innovator in our space, and the dating environment they've created has struck a chord with a younger demographic. " said Greg Blatt, CEO of IAC, in a press release. "We know that many people who start out on advertising-based sites ultimately develop an appetite for the broader feature set and more committed community, which subscription sites like Match.com."

Blatt seems to believe that OkCupid has the potential to usher younger, more casual users into more formalized, extensive online dating as it exists on Match.com, in what Blatt calls "a seamless evolution of the online dating experience" accomplished "without ever having to leave our portfolio of sites."