A source close to Griffin tells ET that the show's sense of humor was always out of step with hers. In an email leaked by Buzzfeed, Griffin apparently emailed friends and asked them to post messages of support on social media, if they felt comfortable doing so. She also expressed concern about how her departure would be received. "I am nervous and scared about this... " the email reads.
A source close to Fashion Police tells ET that another factor in the 54-year-old comedian's departure was Griffin's concern that the Zendaya scandal -- in which Rancic made the controversial comment that the 18-year-old Disney star's dreadlocks hairstyle at the Oscars smelled like "patchouli oil ... or weed" -- could negatively affect her current arena tour and concert sales. Griffin has a concert stop scheduled as early as Friday, March 12, in Waterbury, Conn., and has regular scheduled appearances across the U.S. through October.
The source also adds that E! didn't exactly try and stop her from quitting.
Just last month, Kelly Osbourne -- who had been part of the Fashion Police cast for five years -- also abruptly quit following her own outspoken unhappiness with the Rancic controversy. "I could not be more proud of you @kathygriffin you have my love and support always!" she tweeted on Thursday in reaction to Griffin's decision.
When speaking to ET's Brooke Anderson recently, Kelly expressed that all of the recent Fashion Police drama would never have happened if everyone had listened to the show's executive producer, Melissa Rivers. However, according to a source, Kelly cannot yet speak publicly about her reasons for leaving Fashion Police due to contractual obligations.
But when ET sat down with Melissa in February, she gave no hint that there was any trouble within the cast.
"I love, love, love, love my cast," she said, referencing Griffin and her fellow newcomer, celebrity stylist Brad Goreski. "Right now, I love my cast, I love the direction the show is going. As I've said in the past, it needed to feel familiar yet completely fresh and different, and I think we're achieving that, so I'm really proud of them."
But in Griffin's lengthy Instagram post explaining her decision to leave, she directly expressed that she was at odds with the creative direction of the show.
"I do not want to use my comedy to contribute to a culture of unattainable perfectionism and intolerance toward difference," she wrote. "I want to help women, gay kids, people of color and anyone who feels underrepresented to have a voice and a LAUGH!...After 7 episodes of Fashion Police, I discovered that my style does not fit with the creative direction of the show & now it's time to move on."
Griffin has already received plenty of support from her fellow celebs for the decision, including Chelsea Handler, who has been more than vocal about how little she respects E!.
Watch the video below for more of Griffin's recent comments on Fashion Police and the Zendaya scandal, including why she refused to participate in a planned running segment of the show titled "Whore Score."