Schwarzenegger, Maria Shriver: Behind the split

A Hollywood and political dynasty is ending.

Bodybuilder-turned-actor-turned-governor Arnold Schwarzenegger and his wife, Maria Shriver, say they are separating after a quarter century of marriage.

As CBS News National Correspondent Ben Tracy reported on "The Early Show," they were all smiles as recently as Saturday, when they celebrated the graduation of their nephew. But -- Shriver wasn't wearing her wedding ring.

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"They have been leading rather separate lives" since Schwarzenegger's term as California governor ended," says TheWrap.com Editor in Chief Sharon Waxman. " ... What has emerged is that Maria has chosen to leave their Brentwood (California) home."

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The quintessential California power couple entered a new phase of their marriage when Schwarzenegger was elected Governor. But since his term ended, the two have been apart more than they've been together, Tracy says. Schwarzenegger has been making plans to re-start his film career with another "Terminator" movie. And Shriver worked as an editor at Oprah Winfrey's magazine while considering her future career options.

In a March 28 YouTube video, Shriver says, "It's so stressful to not know what you're doing next. I'd like to hear from other people in transition -- personal, professional, emotional, spiritual, financial. How did you get through it?"

The couple issued a joint statement announcing their separation, saying in part, "This has been a time of great personal and professional transition for each of us... We ask for compassion and respect from the media and the public."

They said nothing about divorce -- only that they are living apart while they work on the future of their relationship.