The former Pussycat Dolls singer met Donnelly while filming hit U.K. reality Tv show I'm A Celebrity... Get Me Out Of Here!, of which he is co-host, last year (12) and the pair struck up a friendship.
Donnelly made no secret of his crush on the star during her stint in the Australian jungle-based challenge show and now it appears the pair have become closer.
Roberts tells Britain's Daily Mirror, "We're trying to keep it out of the public eye. We're just getting to know each other. We're having fun but I'm single."