Singer/actress Ashlee Simpson, the younger sister of Jessica Simpson, has filed for divorce from musician Pete Wentz.

The pair married in a lavish ceremony in May 2008 and have a two-year-old son Bronx Mowgli.

Ashlee, 26, cited 'irreconcilable differences' in the documents filed in Los Angeles County Superior Court on Tuesday.

The split comes as a shock since the couple were pictured only last Friday having a coffee, showing no signs of an impending separation.

In a joint statement, they said: "After careful consideration, we have made the difficult decision to file for divorce.

"We remain friends and deeply committed and loving parents to our son Bronx.

"(His) happiness and well-being remains our number one priority."

Photo: © Rex