Maria Shriver and son Patrick Schwarzenegger went to Gartner Studios in Santa Monica. Credit: Splash News

While Arnold Schwarzenegger is promoting his new tell-all book on the collapse of his marriage, estranged wife Maria Shriver is spending quality time with their son.

Shriver, 56, stepped out Thursday in Santa Monica, Calif. to grab lunch with son Patrick, 19. The journalist, who kept her head down and shades on while passing by photographers, has continued to live a separate life from her ex.

In Schwarzenegger's memoir, Total Recall: My Unbelievably True Life Story, the 65-year-old former Republican governor of California opens up about how his extramarital affair -- with housekeeper Mildred Baena that resulted in the birth of his fifth child -- "destroyed my family."

Shriver filed for divorce from Schwarzenegger in July 2011 after 25 years of marriage. They are parents to Katherine, 22, Christina, 21, Patrick and Christopher, 15.

"Maria has been extraordinary throughout this whole process," Schwarzenegger explained to Fox News' Hannity on Oct. 1. "Extraordinary also with bringing the children together and making sure that we celebrate together when there's a graduation or when there's a birthday or Valentine's Day or Easter, or Christmas -- stuff like that. She's been great. The kids have been really great. I'm thankful about that."

And he is hoping for a reconciliation with Shriver. The Expendables 2 star said he sees them getting back "together eventually. It takes a lot of time to heal those wounds and to trust each other again. But, you know, I will make every effort."