Schwarzenegger and wife Shriver to separate

In a statement, the couple said it had been a time of “great personal and professional transition” and they had reached their decision together after much reflection, discussion and prayer.

“At this time,” they said, “we are living apart, while we work on the future of our relationship,” and appealed to the media to allow them and their four children some privacy. Shriver will be moving out of the mansion in Brentwood, Los Angeles, while they work out their next step.

The union of an Austrian bodybuilder turned Hollywood action star turned Republican politician, and one of America’s starriest political clans, the Kennedys, was always an unlikely partnership – yet they have been married for 25 years.

The couple first met at a tennis tournament in 1977, when they were introduced to each other by the TV anchor Tom Brokaw, and married nine years later.

The union was always an unlikely partnership – yet they have been married for 25 years.

Shriver, a dynamic figure in her own right, has been an integral part of her husband’s political career, her Democratic heritage endowing him with a certain legitimacy when he decided to run for office.

During that crucial recall election in 2003, she rallied to his defence after a series of stories in the Los Angeles Times accused him of groping and womanising. “I don’t get into specifics”, she said, standing at her husband’s side, and declared that the allegations “show why really good people don’t want to go into politics any more”.

Indeed, the couple even seemed to thrive on their political differences – in 2008 Shriver publicly endorsed Barack Obama’s Presidential campaign, while her Republican partner backed John McCain.

Since leaving office, Schwarzenegger has hinted he is eager to return to the entertainment business, with a comic book and television show based on his nickname “The Governator” in development. He has even signed on to do three films, including another Terminator movie.

‘I’d like to hear from other people in transition. How did you get through it?’ Maria Shriver on YouTube

Shriver, who gave up her career as a correspondent on NBC’s Dateline after her husband became Governor, has recently worked on a number of journalistic projects as well as her many volunteer projects.

In a YouTube video back in March, she told supporters it was stressful not to know what she would be doing next, and appealed for help: “I’d like to hear from other people in transition. How did you get through it? What were three things that enabled you to get through..?”

In the last few months, the couple have rarely appeared together. Now it seems their increasingly separate lives have led to the “amicable separation” which was formally announced today.