Mischa Barton's Ex Cisco Adler Is Engaged

Credit: Jesse Grant/WireImage.com

Sorry, ladies: Cisco Adler is off the market.

The musician and ex-boyfriend of Mischa Barton and Kim Stewart proposed to his model girlfriend, Barbara Stoyanoff, about a month ago.

"They are very happy," a source tells UsMagazine.com.

The two are set to walk down the aisle in February.