A spokesperson for the Operation Transformation host confirmed that Kathryn (33) split from Enda Waters during the summer.
The pair kept the break-up under the radar for the past couple of months -- but news of their split emerged this week.
When contacted by the Herald this morning, Kathryn said she did not wish to comment.
It is thought the pair mutually decided to go their separate ways in July and Enda has moved out of the home they shared.
"They split up in July, but have been trying to keep it quiet as they both don't want to make a fuss," a friend has said.
Kathryn, who also presents top RTE show The Voice, has just returned from a 10-day trip to Los Angeles.
And she appeared alongside radio host John Murray this week as the pair kicked off the search for the next batch of Operation Transformation leaders.
Sources said Kathryn has no plans to date any time soon.
"For Kathryn, she's now got over the split and isn't dwelling on it too much -- it's something she doesn't want to do," said a source.
Kathryn recently told the Herald that she is "busy but it's a good complaint" as work becomes her number one priority.
Kathryn had not been seen publicly with her traffic garda boyfriend since they were spotted together at the wedding of Kathryn's RTE colleague Daithi O Se to Rita Talty at the beginning of July.
The couple also enjoyed a holiday in the sun together when they jetted over to Dubai in April.
In the same month, Kathryn admitted that the couple had no plans to marry but were happy.
"I'm always denying getting wed, but no, not yet, we are very happy as we are.
"Each to their own, I have an independent streak and I have a partner who accepts that luckily," added Kathryn.
Kathryn met Enda at a charity ball for the Mater Hospital in 2007.
The couple then became friends after meeting at another event months later before starting a relationship.