The actor, who has signed a new £200,000 deal to play David Platt, is still sharing a house with long-term fiancée Lauren Shippey.
But the couple have confided to close pals they are “over” and it is “just a matter of time” before they go their own ways.
Jack and Lauren, both 29, got together aged 14.
Lauren threw him out in 2011 when a DNA test revealed he was dad to a baby boy after a one-night stand with sales executive Sammy Milewski.
But Jack successfully begged her to take him back. He gave her a £3,000 engagement ring.
At the time a friend said: “Lauren understands Jack made a terrible mistake.
"Now he has made the ultimate statement that he wants to be with her for the rest of his life.”
Last night another pal confirmed: “They have been through a lot but are still young enough to sort themselves out for the future.”
Jack and Lauren, of Boothstown, Manchester, have an eight-year-old daughter and a son aged three.
A spokesman said in a statement: “Jack and Lauren remain the best of friends and their main focus is the care of their children.”