No one could possibly interpret what you said in any other way unless they assume you were being sarcastic. It's not ambiguous. If you didn't mean what you said, either you were being sarcastic or you wrote it incorrectly.
The thing you said means "Polyamorous people are toxic because they cause other people to feel jealousy, and jealousy is toxic." It does not mean anything else. If you meant something else by it, your English is too bad to be writing a game in English.