Simpson began dating Fall Out Boy bassist and songwriter Wentz in 2006 and by February 2008, she was wearing a diamond ring. She explained that it was a promise ring from Wentz.
By April of that year the couple confirmed their engagement and got married on 17th May 2008 at her parent's house in Encino, California. Her father officiated the ceremony. She wore an ivory lace wedding gown by Monique Lhuillier and jewellery by William Noble. Guests at their wedding included Jessica Simpson, Tony Romo, Joel Madden, Nicole Richie and Donal Faison. (IMDB)
She changed her surname to Wentz and while they were together, she was professionally known as Ashely Simpson-Wentz.
Just two weeks after the wedding the couple revealed they were expecting their first baby and she gave birth to their son Bronx Mowgli in November 2008. Wentz said the reason for their son's name "comes back to a very specific story between me and my wife. But I would just like to say that it wasn't because either of us were trying to give our son street cred. At the end of the day, we like the name. Brooklyn gets a lot of love. It's time for the Bronx to get a little bit of love too." (Wikipedia)
On February 2nd 2011, Simpson filed for divorce from Wentz citing 'irreconcilable differences' and requested that her maiden name be restored. Their divorce was finalised on 22nd November 2011.