"They genuinely did care about each other and worked very hard to protect their relationship," an insider close to the Sex and the City cast tells PEOPLE

Kim Cattrall, Sarah Jessica Parker, Kristin Davis, Cynthia Nixon spent years combating rumors that there was tension between the four of them while filming their Emmy-winning HBO series and its two big screen sequels. But a source close to production tells PEOPLE the actresses had conflicts and consciously kept that from fans.

“They genuinely did care about each other and worked very hard to protect their relationship,” the insider says. “Every relationship has its ups and downs and they worked very hard to protect fans from moments that weren’t ups.”

Multiple sources tell PEOPLE that star Kim Cattrall’s demands led studio Warner Bros. to kill Sex and the City 3, which Parker had said had a “beautiful, funny, heartbreaking, joyful, very relatable script and story” ready for filming.

Sources have told PEOPLE that Cattrall made “outrageous demands” to re-board the movie franchise. Another source previously countered that Cattrall was not happy with the “humiliating” plotlines for her character in the movies. (Warner Bros. has not commented).

While Cattrall has since denied that her demands had anything to do with the death of the in-development sequel — which she said she refused to board back in 2016 — an insider tells PEOPLE that the actress is refusing to own up to her part.

“It’s amazing Kim is saying she wasn’t negotiating because she was absolutely asking for many demands, some of which have already been quoted,” says the insider. “When she said the relationship was toxic, it’s interesting because she is the one who creates the drama, but she won’t take honest responsibility for her actions. She’s been protected by their silence for so long I think she just expects that.”

Cynthia Nixon, Kim Cattrall, Kristin Davis and Sarah Jessica Parker
| Credit: Ian West/PA Images/Getty Images

Rumors that Samantha (Cattrall), Carrie (Parker), Charlotte (Davis) and Miranda (Nixon) were reuniting for a new film — which would follow 2008’s Sex and the City and 2010’s Sex and the City 2 — had long swirled, with fans hoping to see the fierce foursome reunited again

After almost eight years of encouraging words from actors, Parker told Extra on Sept. 28 that any possibility of a third movie is officially “over.”

“It’s not just disappointing that we don’t get to tell the story and have that experience, but more so for that audience that has been so vocal in wanting another movie,” she said.

sarah jessica parker - news
Kim Cattrall and Sarah Jessica Parker
| Credit: Bryan Bedder/Getty

In the aftermath, Cattrall, 61, sat down with Piers Morgan for ITV‘s series Life Stories, calling the drama a “toxic relationship” and claiming, “I never asked for any money, I never asked for any projects. To be thought of as some kind of diva is absolutely ridiculous.”

Cattrall then called out Parker — who would have been a producer on the film. “And this is really where I take to task the people from Sex and the City and specifically Sarah Jessica Parker in that I think she could have been nicer,” she said.

RELATED VIDEO: Kim Cattrall Slams Sarah Jessica Parker as Tensions Surrounding SATC 3 Revealed: ‘Kim Killed the Movie,’ Says Source

On Friday, Cattrall said she’s moved on from playing powerhouse PR maven Samantha Jones — and wants fans to move on too.

“I’ve played ‘SAM’ for 20 years. Am moving on & so should you,” Cattrall wrote back to a fan questioning why she had said she’s leaving, then plugging her recent two-season Canadian comedy series Sensitive Skin, which is streaming on Netflix. “Trying #SensitiveSkin my show on @Netflix.”