A-Roid and Britos dined at the tony Scarpetta restaurant at the exclusive Fountainebleau resort on the beach, openly allowing photographers to approach the table and snap the pair, the New York Daily Newsreports.
Madonna pal Ingrid Casares later joined the couple at the restaurant -- but the pop diva did not make an appearance.
Onlookers who dined at Scarpetta with Rodriguez, 33, and Britos told the Daily News they looked every bit the happy couple.
"They were not holding hands, but they looked very happy; he seemed very into her," one patron said.
"He really likes her. I don't think this is just about making Madonna jealous," another customer added.
Britos, who specializes in modeling bridal wear, has posed for Bridal Fashion magazine and various wedding Web sites.
The Yankee and his new girl reportedly met last November at the Fountainebleau -- so the romantic locale was meaningful for the pair.
Madonna, 50, is reportedly seeing much-younger model Jesus Luz, 22. The two were spotted in the Miami Beach area earlier this week, but there was no word on whether the pair spent the lovers' holiday together.