Caroline, who will take to the dance floor in this weekend's Strictly semi-finals, has been dating Jack for 18 months and they live together in London.
However, it has today been claimed that their romance has fizzled out, leaving the former Xtra Factor host "heartbroken".
A source told The Sun: "It came to a natural end and was mutual. No one else is involved."
In September, Caroline spoke about how Jack had been helping her with her dance moves in the kitchen at home.
She said: "Me and my boyfriend have done a bit of practice in the kitchen but that really is about it.
"The only problem is that my boyfriend is the worst dancer I have ever seen in my entire life! Although to be fair he really does try hard though even if he does move like a mosquito, haha!"
Reveal contacted Caroline's rep but he had no comment to make. If the reports are true, it could mean the star has fallen foul of the 'Strictly' curse.
Celebrities who have suffered relationship splits after appearing on the BBC One dancing show include Denise Van Outen, Former rugby player Ben Cohen and Good Morning Britain's Susanna Reid.
In April, Caroline told Cosmopolitan that Jack had moved into her house, adding that they worked hard to keep the spark alive.
She explained: "We're lovers, not best friends.
"You have to make an effort; go on dates. Fancying each other is so important in a relationship. We don't talk about intimate problems or periods. You've got to keep the mystery."
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