Mr McCarthy, a former television journalist, refused to talk about his relationship with Ms Morrell when he answered the door of his late father's home in Cornish Hall End, Essex. He said: "It is true we have separated - but I do not want to talk about it. I am not giving interviews or making any comment."
Their agent, Mark Lucas, said the break-up, almost four years after Mr McCarthy, 38, was released from captivity,was "very sad" and an amicable decision - "nothing dramatic".
Mr McCarthy was acting Beirut bureau chief for the TV news agency WTN when he was seized by Muslim extremists in April 1986 as he drove to the city's airport.
He was kept chained to a radiator, stripped to his underpants, blindfolded and beaten for 1,943 days.
Ms Morrell, his girlfriend for the previous three years, campaigned constantly to keep his plight in the public eye, confronting Margaret Thatcher and Yasser Arafat. Halfway through Mr McCarthy's captivity she said she could no longer be considered his girlfriend because she did not know if he was alive or dead. "A future with John had begun to seem more like fantasy as time went on ... I didn't want him to feel obligated. I didn't want to put pressure on John, to make him feel he had no choice but to come back to me," she said.
After his release on 8 August 1991, they went on holiday together to France and retired to Oxfordshire to write their account of their ordeal, Some Other Rainbow. Despite the public's hopes of a happy ending the couple did not get engaged immediately, nor was there any sign of a future engagement.
Canon John Oates from St Bride's Church in Fleet Street, where a permanent vigil for Mr McCarthy was held during his imprisonment, said the couple were "still very close friends" and would remain so. "Everyone else is trying to make it a great love affair and longs for them to get married," he said. "But they need what all couples need, an opportunity to have space."
Canon Oates said Mr McCarthy was scarred, as all the hostages were, and it would take a long time for him to heal.
Medical experts who examined Mr McCarthy said he was the most traumatised of the hostages. He was described as having encountered the most problems coming to terms with his experience.
A close friend was quoted in the Sun yesterday as saying: "All either of them wanted was the chance to be an ordinary couple living ordinary lives, yet the pressure of their ordeal, and the pressures of a fairytale ending took its toll ... despite what the public wanted so much it probably never stood a chance."
Leading article, page 16
Section Two, cover story