A man is claiming he had a 10-month-long affair with the Colorado dad accused of slaying his pregnant wife and their two toddler daughters.

The anonymous man from Loveland, Colorado, claimed Tuesday that he met Chris Watts, 33, on an app called “MeetMe” and that the pair began a sexual relationship when they saw each other in person for the first time in June 2017.

“It was clear that he was interested in me and attracted to me,” the man said on HLN’s “Crime & Justice” show. But Watts allegedly told him he was “not out and not ready to be out as far as his sexuality.”

“I had asked him if he’s sure he’s not bisexual because obviously, he had two children, but he told me he didn’t know, and at that moment he was attracted to me and me as a man.”

The man said Watts never told him he was married — but that he found out in late January or early February when they were driving around with Watts’ daughters Celeste, 3, and Bella 4.

“Bella made a comment and asked him if she could sleep with him and mommy tonight and that’s when I found out,” he said.

But Watts reportedly assured him that he and his wife, Shanann Watts, 34, weren’t happy at home, and were no longer sleeping together.

“He told me his wife was verbally and emotionally abusive, that he didn’t love her and that it was clear she didn’t love him.”

He added: “I knew something was wrong at home because obviously if nothing was wrong, he wouldn’t have pursued me.”

Eventually, the man said he broke it off when Watts kept telling him lies. He said he felt “ill” when he found out that Watts was arrested this month in the slayings of his wife and two daughters.

According to court documents, Watts had been having an affair with a co-worker. The anonymous man said that he imagined the co-worker could be either a man or a woman.

Friends of Shanann Watts also claimed she had told them she suspected her husband was having an affair.

The mom was 15 weeks pregnant when she was found dead Aug. 16., along with her two girls.

HLN’s host Ashleigh Banfield said the show sought the man to speak out but that it couldn’t independently confirm his story.