Maria Shriver, Arnold Schwarzenegger: Shriver Files for Divorce

July 1, 2011— -- Maria Shriver has filed for divorce from actor and former California Gov. Arnold Schwarzenegger.

Shriver cited "irreconcilable differences" as her reason for ending the 25-year marriage, according to her divorce petition filed today in Los Angeles County Superior Court, a copy of which was obtained for ABC News by its Los Angeles affiliate, KABC.

Shriver is seeking joint legal and physical custody of the couple's two minor children, Patrick, 17 and Christopher, 13, and a division of assets, according to the divorce papers. The couple also have two older children together, Katherine and Christina.

There is no prenuptial agreement, KABC reported.

Shriver and Schwarzenegger announced in May that they were separating after Schwarzenegger admitted fathering a child, Joseph, with a family housekeeper, Mildred Baena, 14 years ago.

Shriver moved out of the couple's home in the Brentwood section of Los Angeles.

The couple jointly announced in May that they would live apart while "they decide on the future of their relationship. ... This has been a time of great personal and professional transition for each of us. After a great deal of thought, reflection, discussion, and prayer, we came to this decision together."

Baena told Hello! magazine in an interview published in June that Shriver had an inkling of her husband's secret as she heard talk around the house of Joseph's physical similarity to his father.

According to Baena, when Shriver asked her about her son's paternity, she admitted that the governor was indeed the father. Reportedly, Shriver then hugged Baena and cried with her, telling her to "get off [her] knees."

Baena expressed hope for a reconciliation between Schwarzenegger and Shriver, saying Schwarzenegger "is suffering," adding, "He loves Maria. I hope in time they work things out."

The marriage always seemed an odd political alliance: Schwarzenegger, 63, is a Republican from Austria while Shriver, 55, is a member of the Democratic Kennedy family.

President John F. Kennedy was her uncle. Her mother was the founder of the Special Olympics. Her father founded the Peace Corps in the Kennedy administration.

Amid prior allegations of affairs that threatened to derail Schwarzenegger's political career, he admitted that he "behaved badly" and Shriver stood by him. She later went on television's "Oprah" and denied Kennedy women "always look the other way."

Shriver has worked as a correspondent for CBS and NBC News and in recent years was devoted to many social causes, including Alzheimer's disease, which her father, Sargent Shriver, suffered from before his death in January. Schwarzenegger, a former bodybuilder, made his name in films such as "Terminator" and "True Lies." The couple left the governor's mansion in January.

Elements of an earlier report by Helen Zhang contributed to this report.