The 36-year-old funnyman separated from the mother of his two young sons, Archie, five, and Harvey, three, at the end of last year and is currently enjoying a sun-filled break in Florida with his new girlfriend.
A friend of the star told the Mail today: ‘Justin and Karen have separated and he does not want to talk any further about it or go into any more details.’
Collins' new girlfriend is believed to be video games developer Anna Larke, who is in her early Thirties.
Throughout his marriage, Justin was linked with a string of other women and three years ago, the Channel 5 host was forced to deny reports he had cheated on his wife with old friend Ann Finan.
He told the News Of The World: 'Every marriage is different.
‘My wife and I have been together for 12 years. Our marriage works and we are totally OK.’
After being seen kissing and groping Finan at the Grain Barge pub in Bristol, Justin admitted his behaviour could be construed as ‘inappropriate.’
Finan added: 'I have known him a while. We had too many drinks and stepped over the mark. I have nothing else to say.'
But it was more than clear that Justin was ready to move on as his new girlfriend squeezed lemon juice on to his famous bushy hair to top up his blonde highlights.
The couple looked extremely cosy as they soaked up the sun on Miami Beach and were very affectionate as they kissed and cuddled on the beach.
The friend said: ‘Justin doesn’t want to talk about his new partner.’
