The American Idol judge and singer began dating background dancer Smart in November 2011, shortly after her divorce from husband Marc Anthony.
Lopez praised her 24-year-old love interest in a new interview with Vogue, though she insisted that she prefers to keep her romantic life private.
"He's adorable. But you already see that," Lopez told the publication. "He really is [sweet]. He's a good egg. I don't want to talk about it too much. It's my private thing."
Lopez also addressed the 20-year age difference between herself and Casper, insisting that it has never affected the couple's connection.
"I don't feel older, and I don't feel like I look it, either, so I am just acting the same way I have always acted," she said.
Lopez's long-time manager Benny Medina recently confessed that he wished the star would date "less obsessive" men.
> Jennifer Lopez boyfriend Casper Smart: 'Age, status irrelevant'