He also admitted the five years of work on his book had “deeply affected” him and led to him undergoing residential treatment for trauma late last year.
The publication reported the earl has now grown closer to Cat Jarman, the Norwegian archaeologist he co-hosts The Rabbit Hole Detectives history podcast with, alongside Reverend Richard Coles.
Friends said they look very happy together but it is “early days” for the pair.
Charles and Karen - who have 13-year-old daughter Lady Charlotte together - are believed to have told staff at their Althorp estate about their plans to divorce back in March.
The pair married on the family estate in June 2011, a year after they first met on a blind date.
Charles previously told the Sunday Times newspaper of their relationship: “Karen and I both appreciate what the other does and look after what we have. Neither of us has found happiness like this before.”
As well as Charlotte, the earl also has four children with first wife Victoria Lockwood and two with second spouse Caroline Freud. Canadian entrepreneur Karen has two daughters from her marriage to Hollywood producer Mark Gordon.
The earl recently spoke on Sunday with Laura Kuenssberg about how he had to seek counselling at a “residential treatment centre” last year due to the “trauma” of reliving the abuse during the writing of the book, which he said sparked a “breakdown”.
Charles added: “Confronting ... evil is a very, well, it’s cataclysmic really.
“I’ve always been intrigued by what humans are capable of doing for each other.”
When asked how detailing his experiences of abuse in his book had affected him, Charles said he was taken to a “very dark place” and added: “I had endless nightmares.”
