This is so far only speculation and assumption based on Zach Bryan cheated on now ex-girlfriend Brianna Chickenfry. In the article it does say that viewers are assuming that Zach cheated, but it's not actually confirmed by either party. The article does mention speculation about another female "Brooke" who was supposedly with Zach summer of 2023 and had taken to social media with proof, but at the same time, it is still unconfirmed by Zaach or Brianna that Zach did fact cheat or not. Brianna did take to social media after Zach posted saying he and Brianna had broken up saying she was blindsided by his post and that she also felt betrayed by him ending the long-term relationship. Overall it seems to just be speculation of cheating at the moment, but that could change if either he or Brianna decides to confirm or deny it.