Lisa Rinna and Denise Richards had a friendship before the latter joined The Real Housewives of Beverly Hills, but they might not have one after season 10. The two women had a falling-out while filming the upcoming season of the reality series, Us Weekly can exclusively reveal.

“Behind the scenes, Lisa Rinna is continuing to be the instigator and continuously stir the pot for maximum drama. Rinna does this to make herself relevant and maintaining job security,” an insider tells Us. “Denise has had enough of Rinna’s constant meddling and passive aggressive behavior, especially with social media. Denise and Rinna are headed toward a showdown on camera, which is what Rinna has wanted.”

The insider adds, “Rinna is going to be exposed and held accountable; if Denise is the one to do it, bring it on.”

Earlier this month, the 56-year-old Melrose Place alum called out the Bold and the Beautiful star, 48, for skipping an event at Dorit Kemsley’s house.

“Denise are you ok? You never showed up to Dorit’s Sat night we were all so worried about you. What happened?!” Lisa commented on Denise’s Tuesday, December 17, Instagram post about a recent health scare. “You said you were coming, you were meeting Garcelle [Beauvais], We never heard from you. What happened ?”

While Denise has yet to publicly respond to Lisa, Camille Grammer came to her defense the following day.

“Denise did not quit #rhobh and Rinna you throw your friend under a bus,” the 51-year-old tweeted on Wednesday, December 18. “How about calling her to see how she’s Doing and stop tweeting about it.”

Lisa quipped back, “I did reach out to her privately. Thank you for your concern, Camille.”

Brandi Glanville, who will have a recurring role on season 10 alongside Camille, then got involved in the drama. “Ive been asked not to get involved and i won’t but I have sooooo many things to say about A certain someone tweeting at certain other person to get off Twitter… R U serious !!!!!” the 47-year-old Celebrity Big Brother alum tweeted on Thursday, December 19, seemingly shading Camille. “Pot call kettle.”

The Real Housewives of Beverly Hills, which also stars Kyle Richards, Teddi Mellencamp, Erika Jayne and newbie Sutton Stracke, will return to Bravo in 2020.