Los Angeles ( CNN ) -- Maria Shriver cited `` irreconcilable differences '' in a petition filed Friday to dissolve her 25-year marriage to former California Gov . Arnold Schwarzenegger . The move comes more than a month after Schwarzenegger acknowledged that he fathered a child outside of his marriage . The couple announced their separation on May 9 , calling it a mutual decision made `` after a great deal of thought , reflection , discussion , and prayer . '' It became clear a week later that the split was triggered by Schwarzenegger 's revelation to his wife that he had fathered a child with his housekeeper . `` After leaving the governor 's office I told my wife about this event , which occurred over a decade ago , '' Schwarzenegger said in a statement May 17 . `` I understand and deserve the feelings of anger and disappointment among my friends and family . '' Shriver , in a written statement that same day , described it as `` a painful and heartbreaking time . '' `` As a mother , my concern is for the children , '' she said . `` I ask for compassion , respect and privacy as my children and I try to rebuild our lives and heal . I will have no further comment . '' It was confirmed several days later that a son fathered by Schwarzenegger with his housekeeper was born less than a week after Shriver gave birth to Schwarzenegger 's son , Christopher , who is now 13 . Shriver 's signature on the divorce papers is dated June 18 , but her lawyer filed them with the Los Angeles County Superior Court on Friday . Shriver 's petition proposed that she and Schwarzenegger share joint custody of their two minor sons , Patrick , 17 , and Christopher . They also have two adult daughters , Katherine and Christina . The date of their separation was listed as `` to be determined . '' The filing did not detail the assets to be divided between Shriver and Schwarzenegger . `` There are community and quasi-community assets and obligations of the parties , the exact nature and extent of which are unknown to petitioner at this time , '' Shriver 's petition said . Schwarzenegger , a naturalized U.S. citizen from Austria who gained fame as the youngest winner of the Mr. Universe bodybuilding contest , was governor until January . He has been busy in recent months reviving his acting career and signing movie deals -- including plans for another installment of the `` Terminator '' series . CNN 's Paul Vercammen contributed to this report .
NEW : Shriver wants joint custody of the couple 's two minor children . Shriver and Arnold Schwarzenegger split after more than 25 years together . He has admitted to fathering a child outside of his marriage . Shriver and Schwarzenegger share four children .