Although the 55-year-old writer "didn't suspect for one second" that the 'Terminator' star had fathered a child 14 years ago with former housekeeper Mildred 'Patty' Baena, she reportedly had her suspicions about other workers.
A former employee said: "Maria didn't suspect for one second that Patty was messing about with her husband. But there were others who she wasn't quite so sure about.
"It's perhaps little surprise that after suspicions were aroused, they subsequently didn't last long in employment."
It was also revealed Mildred, 55, was given access to parts of the former governor's home that were out of bounds for other members of the household staff, and was even allowed to use the family car to run errands.
The insider told the Daily Mirror newspaper: "Arnold treated her like one of the family and all the staff knew that they were very close. It was pretty obvious that something was going on - but Maria seemed to turn a blind eye.
"People have been with them for decades. For all Arnie's faults, he's a great boss - as is Maria."
Meanwhile, Katherine Schwarzenegger - one of the estranged couple's four children - has deleted posts on her twitter page, which suggested she was ready to "forgive" her father for his actions.
She had written: "Sometimes we forgive people cause we want them back in our lives. (sic)"
However, it has since been replaced with: "As my healing begins after this crazy week I ask for privacy! This is only the business of my family and please respect that!"