For what it’s worth, I’m poly and I disagree with that characterization. Polyamorous relationships are held to a different standard.

A monogamous relationship where everyone isn’t having their needs met can continue in perpetuity, for one reason or another. Such a polyamorous relationship is more unstable and likely to end more swiftly and decisively. It’s possible to see that as a good thing.

(If you buy this reading, “open relationships hurt marriages” isn’t a story about failing poly relationships, it’s a story about monogomous relationships that already failed without anyone noticing.)