The country singer - who has two daughters, Sunday Rose, two, and three-month-old Faith, with the actress - checked into a Clinic to be treated for drug and alcohol abuse just four months after he married the 'Rabbit Hole' star in June 2006, and he now realises the reason he was took substances was to make up for the lack of "intimacy" in his life.
He told Good Weekend magazine: "I think I've spent my life fearful of intimacy. The result was a feeling of 'being without', this hole I tried to fill with all those other things. The only thing that has really filled it has been the love of my wife and our daughters."
Keith wishes he had met Nicole earlier in his life, but he is now grateful for every day he gets to spend with her.
He added: "The way in which it happened has turned out to be divinely inspired."
Keith has previously admitted he was terrified his stint in rehab would destroy his marriage to Nicole, who staged an intervention with some of their friends.
The musician - who had been to a treatment clinic on two prior occasions - said: "I thought, 'Surely let's give it a few years so we've got some solidity, because this kind of thing could tear us apart. This could just destroy us.'
"It was really a profound moment in so many ways. The way in which Nic handled that moment was just perfect ... Everything was just designed, I believe, for that moment to fuse us together."
After having a music career that spanned five decades and saw the release of over...