There is one little thing I've noticed among younger poly's I know. And that's quite a few. Love is the key. What is love, and how is it expressed? We can't really say can we? We can only say indirectly. So we have to nail that one down first... which means skills in expressing one self.... and empathy ... understanding each other... and so on. It needs extremely mature and intelligent people. I'm not saying it can't work anyway just out of dumb luck. I suspect that I really only notice the poly relationships that don't work since those who do just seem like people being very good friends. But the jealousy and drama is super easy to pick up on at a party. ...and that's pretty much my perception of poly for young people. It's like an endless episode of your favourite soap opera. Drama, drama, drama. ....but maybe that is what they want
I have an example of a very well functioning poly situation close to home so I know very well how well it can work when it does. It's also fascinating to see when any of them date somebody who say they understand and are down with it... when they aren't. How they try so extremely hard to push on all the jealousy buttons and nothing works.
Some people do define love in terms how far others would go for them. The jealousy factor. People like that are obviously not poly material.