updated 02/11/2011 AT 12:00 PM ET
•originally published 02/11/2011 AT 3:05 PM ET
“It was honestly a classic case of marrying young, having a kid young and growing apart over the years,” says source, who is close to Simpson. (The couple wed in May 2008 when Simpson was 23 and Wentz was 28.)
For the famous young pair, the demands of career versus family also caused strain on the relationship. “When you don’t spend a whole lot of time together, things become challenged,” says the source.