But Moore said the rumors are bunk.
Stewart used to be married to Moore's Real Housewives co-star Porsha Williams.
He also denied he was having an affair with Moore.
"There is a beautiful lady who I am very interested in," he told HipHollywood, "however, it is not Kenya Moore."
The country singer made the quip on a recent episode of In Bed with Joan, hosted by Joan Rivers.
Rivers asked Rimes how old she was when she had sex — 16 — and how it was.
"Was it nice? Was it bad? Was he nice?" Rivers asked.
"Well, he was my boyfriend for like three and a half years," Rimes replied. "He was fine. I think I raped him. I think that's how it happened."
I thought @leannrimes was just cheap entertainment but her joke about rape proved she's ignorant trash. She deserves everything she gets.— Julianne (@Julianne_Gatlin) August 27, 2014
Dear universe: Please boycott @leannrimes forever. Incredibly poor taste & judgement in making rape jokes.— Meghan Meehan-Draper (@MegMeehanDraper) August 28, 2014
Take a look at the clip below. Tasteless?