Deryck Whibley and Avril Lavigne
09/19/2009 AT 02:15 PM EDT
and Deryck Whibley seemed like the perfect rock couple. But at the age of 24, Lavigne began to see things differently, sources tell PEOPLE.
"She married too young and she finally realized that," says a source. "Avril realized she needs her own life and needs to explore things without him."
The couple – who married
in 2006, when Lavigne was 21 – announced their split
on Thursday after weeks of speculation of trouble in the marriage. "I am grateful for our time together, and I am grateful and blessed for our remaining friendship," Lavigne wrote on her Web site
Another source close to the couple, says the duo was having serious problems for at least six months. But, the source states, the split is "not about Deryck wanting a kid nor is she dating anyone else." As for rumors that Lavigne got close with pal Brandon Davis, the sources says, "There is no romance."
The couple, who plan to divorce, are no longer living together in their Bel Air home. "Deryck has left the house," says the source, but "wasn't kicked out."
Both Lavigne and Whibley, 29, lead singer of the band Sum 41, are currently working on new albums.
Additional reporting by JENNIFER GARCIA