Longoria, 38, told People that media speculation about her relationship with Arguello was what brought them together in the first place.
"I think that's why our relationship is so special -- we truly started as friends,” the actress told People. "I guess we have the press to thank for pushing us to see something we didn't see!"
The pair met last year when Arguello, 34, was cast in "Ready For Love," a dating reality show produced by Longoria where the entrepreneur was set up with former Miss USA Shandi Finnessey (they ended their romance later that same year).
Longoria and Anguello remained friends after the show wrapped and eventually became a couple.
"Their friendship and their similar philanthropic interests laid the foundation for their new romance," a source told People. "They're very much in love."