Deryck Whibley and Avril Lavigne Were Living 'Separate Lives.' How Tom Petty Inspired Him to Give a Marriage 'Ultimatum'

Deryck Whibley has revealed what led to the end of his marriage to Avril Lavigne.

In his new memoir Walking Disaster: My Life Through Heaven and Hell (out Tuesday, Oct. 8), the Sum 41 frontman, 44, opened up about the dissolution of his three-year marriage to the pop-punk artist, 40, which stemmed from career changes that led to them being physically and emotionally "distant."

After the punk group released its first middling album which happened to be without former manager Greig Noiri, whom Whibley accused of alleged sexual abuse in his book, Whibley found himself struggling.

Additionally, he suffered a herniated disc that required months of recovery while Lavigne was on tour promoting her 2007 album The Best Damn Thing and her hit single "Girlfriend." While he "couldn't have been more proud" of his ex-wife, he was constantly taunted by the press and was often called "Mr. Lavigne." According to Whibley, there were also reports of Lavigne allegedly "cheating" on him in the press, but he "chose not to believe the rumors."

"There was no single moment or situation that I could point to that caused things to turn," Whibley writes of his marriage in the book. "It wasn’t like it had been going downhill for a while and turned into a bad relationship. We never fought and always seemed totally in lockstep with each other."

While he initially tried to chalk it up to a "passing moment," Whibley needed to eventually address their dynamic.

"Avril and I kept living separate lives until I couldn’t take it anymore," the "Fat Lip" performer writes. "Motivated by the lyrics of Tom Petty’s 'I Need to Know,' I decided to confront our problems and gave her an ultimatum: We had to fix what was broken or I was moving on," he recalls in the memoir.

Whibley was tired of "being humiliated in the media" and hoped that the ultimatum would be "a wake-up call."

"When she was finally at home for a few days, I laid it all out for her," the "In Too Deep" musician writes. “'We have to go back to the respectful loving relationship that we had, or we need to just call it quits,'” I said. 'This isn’t working and I can’t live like this anymore.' Avril told me her decision. There was no crying. There was no big fight. There wasn’t even much of a discussion. It was just over."

Whibley and Lavigne married in 2006 when she was 21 and he was 26. When they announced their split in 2009, a source told PEOPLE the marriage ended because Lavigne realized she was too young to be a wife.

“I am grateful for our time together, and I am grateful and blessed for our remaining friendship,” Lavigne wrote on her website at the time.

Another source close to the couple told PEOPLE that the pair were having serious problems for at least six months. However, they added that the split was “not about Deryck wanting a kid nor is she dating anyone else.”