I can say every poly relationship I have known has ended in flames
I strongly dislike this trope. Most monogamous relationships also end badly. Relationships are hard.
Well they have is all I can say. Two of them ended particularly badly when the person in them who encouraged the poly relationship up and left the person they invited to be poly. My one friend ended up suddenly homeless when her poly couple threw her out after she had moved across country to be with them, and another who had been encouraged by his wife to practice being poly ended up having said wife vacate the premises while he was away for a weekend and empty their bank account and change her number and vanish. Like it was pretty bad.
Right, but you surely have also seen many monogamous relationships also end badly.
Both of those examples could easily have happened with monogamy.
I could rattle off a bunch of poly relationships that have gone well. I know some folks that are raising a kid. They both have other partners. They’re all pretty happy. Been so for years
Another couple has also been together for years. The one of them has had other relationships for years while the other focused on her career. For the last year or two she’s got more time and is exploring dating. She’s having a blast. They’re all very happy.
There’s a friend I’ve known for years that’s done poly the whole time. He’s had some breakups over the years, but that’s just normal relationship stuff. None of them were to my knowledge catastrophic.
I can also rattle off monogamous relationships that went badly.
It’s absurd to be like “monogamous relationships sometimes end badly. Poly relationships sometimes end badly. The poly ones are due to poly.”