Back in April, rumors swirled that Longoria, who was a producer on the short-lived NBC reality dating show, was dating Arguello, one of the three featured bachelors. Longoria says they weren't together at the time, but soon romance blossomed.
"I think that's why our relationship is so special — we truly started as friends," Longoria told People. "I guess we have the press to thank for pushing us to see something we didn't see."
Longoria, 38, and Arguello, 34, recently returned from a trip to Nicaragua where Longoria met the Arguello clan.
"Happy to share NOW that it's true! Couldn't be happier," Longoria tweeted about the news "Me too baby, I LOVE YOU," Arguello tweeted back.
Longoria was previously married to NBA player Tony Parker. Arguello and his Ready for Love pick, former Miss USA Shandi Finnessey, broke up in 2012.