You're hurting, and I'm sorry you're hurting.

"Polyamory" didn't destroy your relationship.

You partner decided to leave the relationship.

What they did was lie to you and use the term "polyamory" as a way to hide what they were doing until it was done.

Why am I telling you this?

Because making broad, sweeping generalizations like you are doing about polyamory prevents you from processing what really happened.

That, in turn, will make it that much harder for you to get on with your life.

You're angry, and you should be angry.

You should also know that anger shrinks your world by causing you to focus on what has angered you, to the exclusion of other things that might be more worthy of focusing on.

I'm asking you to consider assigning the blame to the person who made the decision to behave in a way that was harmful to you, and not to an abstract idea that is not and cannot be to blame for anything.

You might get closure by accepting that what the person did was wrong and that your life will be better without them if that's who they are and how they behave.

I don't think you'll get that kind of closure by assigning responsibility to an idea, an abstract, that some people use as an excuse for bad behavior while others do not.

I don't think that's going to help you.