Isn't polyamory cheating? I understand all parties agree and have each other's consent. Consensual cheating, but STILL cheating, isn't it?
It sounds like you need to do more research. If all parties are in a relationship together, nobody’s cheating on anyone because they are all in a mutually-consensual collective. I get that you can’t wrap your brain around that, I’m not poly either, but you don’t get to tell them that they’re cheating on each other.