The two met during Keating's tour with his band Boyzone in 2009 and went on to have a relationship even though he was married to model Yvonne Connolly, reported Daily Mail online.
"He told me, 'In 20 years, we will be married'," Connolly said.
The affair led to the end of Keating's 14-year-old marriage and eventually he dumped Cornell too.
However, the dancer says Keating's promises sounded convincing.
"It was nice and I think it was what he believed at the time," she said.
Keating, 35, has three children with estranged wife Connolly. The couple married in 1998 and their separation was announced in April this year.
