Mark Owen will leave rehab next month.
The Take That singer - who admitted earlier this month he had cheated on wife Emma Ferguson several times throughout their relationship - is said to be "responding well" to treatment for alcoholism and plans to check out of the unnamed British clinic much earlier than expected.
A friend said: "Initially, everyone thought he might be in the clinic for months but Mark has been responding really well to treatment.
"As a result, it has been decided he will leave the clinic next month."
Although Emma not yet visited her husband in rehab, the 'Greatest Day' singer is still hopeful of saving his marriage.
The source added to the Mail Online website: "Mark knows that when he comes out of the clinic he has to try and persuade Emma to give him another chance. That is what he is preparing himself for now - because no decision has been made on their marriage so far."
Friends of the couple believe Emma, 33, will take back the 38-year-old pop star for the sake of their children - son Elwood, three, and 15-month-old daughter Willow Rose.
A source close to the family said last week: "Emma will do absolutely anything for her beautiful children. Mark has been a complete idiot - which he openly admits - but it doesn't stop him being a brilliant dad.
"He dotes over those kids and Emma knows it. It's a long road ahead. But for the sake of their children, she will forgive him."
Mark's bandmates - Gary Barlow, Howard Donald and Jason Orange - are lending him their full support, as well as former Take That star Robbie Williams.