"We actually met a very long long time ago," the Welsh actor shared on Watch What Happens Live of meeting 16 years ago.
Russell and husband Shane Deary revealed in December that they have been separated since the summer.
She and the single Rhys have been seen in New York City at locations like ABC Kitchen looking “affectionate” and “touchy-feely” with one another, the Post reports.
It could be that the onscreen couple are just getting into character, but this wouldn’t be the first time that life has imitated art with television stars.
PHOTOS: 50 most beautiful female celebrities That rumor certainly sent fan minds into a tizzy when the pair posed for GQ's highly provocative February photo spread that featured a vamped-up Russell in various states of clothed intimacy with her costar. Last December, Russell confirmed her "amicable" split from husband Shane Deary following seven years of marriage.
The pair had been separated since the summer, according to her rep, and have two young children together, River, 6, and Willa, 2.