I am aware that there are quite a few people for whom polyamory and open relationships work and is a valid lifestyle choice for them. They’re happy with each other and both/all partners are on the same level, not jealous and having fun. I know a few people here and there for whom it works. I’m genuinely happy for them and think the legal system should work in their interest etc.
Too common unfortunately appears to be people who use the terms “polyamory” or “open relationships” to mean “so I have this fall back plan partner who is there purely as a security blanket/to legitimise my life while I go and fuck around on the side”. Often in such situations, the partner who is out there getting laid or dating others has the bulk of the power in the relationship. Not uncommonly they are actually gay, have a fringe sexual fantasy they are playing out (and possibly dragging their partner into), don’t have the balls to break it off with a partner they’re no longer in love with or are insecure and this is the only way they feel confident enough to get casual sex or date. The other partner may not be really polyamorous (and only putting up with it because they love the person they’re with), they may also be in a similar boat to the other partner or the more powerful partner gets weird when they go and get some action.
Also terrible – stating that you are polyamorous in order to score someone you’re into when in reality you’re not and are actually trying to trick then.
This sort of thing is really uncool. Using someone else as a security blanket because you are cowardly or have unresolved issues is incredibly unfair to the person you’re with. It’s not real polyamory or open if you can’t deal with your partner enjoying the same advantages as you. If you don’t love someone anymore, you need to let them go so that you can both find someone else. Coercing others into situations they’re uncomfortable with is particularly uncool. And if in reality all you want is casual sex, well you can just have casual sex.
Then there is the assertion that because cheating is common that everyone is intrinsically polyamorous. I don’t even know where to start with that one.