Hilariously, despite its other failings, even the new King of the Hill reboot knows open-relationships (or as they're called in the show, "Ethical Non-Monogamy", or "ENM" for short) are bullshit.
Context: Connie is now in an open-relationship with Chane, that douchebag that used to bully Bobby, and everyone, even fucking Bobby himself, thinks she's being a stupid, massive whore, and that the idea of open-relationships in general is incredibly retarded, and just an excuse for people already in relationships to keep slutting around.