Annie Undone

Cheating in Polyamory?

He Cheated. We Were Polyamorous. Let’s Talk about it.

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Annie Undone
Mar 26, 2026
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a person standing in front of a heart made of fire
Photo by Salah Eddine Haddad on Unsplash

Why I haven’t written this essay in the years since this happened is kind of beyond me. Maybe it felt like talking shit. But I think, also, there is a whole ridiculousness when it comes to talking about cheating and polyamory. Because, for me, it’s like… OMG WHY? You literally don’t have to cheat, you can just be transparent, but that’s also reductive in a way because it skips the whole “why people cheat in the first place.” Which is a varied thing, and I highly recommend Ester Perel’s book, State of Affairs for perspective on this.

Here’s the funny part: I was cheated on in polyamory way more than I have ever been in monogamy. In some ways this is hard for even me to reconcile. What I won’t be doing here is trying to puzzle out the motivations for my ex-husband cheating on me SO MANY TIMES when we were polyamorous. Because, honestly, who knows? However, I do want to talk about what it looked like for me because I think the biggest question I get when it comes to polyamory and cheating is:

WAS I CHEATED ON?

Which is such a great question because what does it even mean to be cheated on in polyamory?

If you go searching for the answer to this, you will probably find that it comes down to broken agreements. The most frequent broken agreements are using barriers during sex, or notifying people before you have sex with a new partner. This will be highly dependent on the relationship, what stage of opening you are in, whether you were previously monogamous before you opened, and other nuances particular to YOUR relationship. Here are four cheating scenarios that happened to me in polyamory…

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