Paula Patton felt "utterly disrespected" by Robin Thicke and Miley Cyrus' MTV Video Music Awards (VMAs) performance.
The 38-year-old actress reportedly had a huge argument with the 'Blurred Lines' singer following the show, saying the raunchy routine - which featured 21-year-old Miley 'twerking' against her spouse - was insulting to her, particularly as it took place in front of a huge national TV audience.
And according to TMZ, Paula was particularly "enraged" because Miley improvised the performance without warning but her husband was happy to play along.
The couple - who announced their separation after eight years of marriage earlier this week - began arguing constantly after the ceremony in August, with the actress particularly furious with Robin's insistence on continuing to party at clubs and frequently being pictured with various women.
Although the couple - who have three-year-old son Julian together - insisted the separation was mutual, friends say Robin fought hard against the decision.
A source told Us Weekly: "Robin wanted to save their marriage, but it was Paula's choice and she ended it. Robin does not want this divorce.
"Robin was not blindsided - he knew this was coming out.But he was committed to saving their marriage. He didn't want this."
Another source added: "She is done with the marriage, but he was definitely fighting to stay together until the last moment.It is still cordial between them, but they are now figuring things out."