Why I Don't Have Relationships With Cheating Partners.

My wife regularly gets emails from men who want to have a relationship with her.  But it’s a special relationship.  They have wives or girlfriends, but they’re combing OKCupid for someone who can keep a secret.
My wife usually doesn’t bother to respond.  Even though we’re polyamorous, cheating partners are a no-go for us.
And that’s not necessarily a moral issue.  It’s just damned good advice in general.
Now, for full disclosure, my wife and I are very pro-other-people’s relationships – even the people we don’t know.  Far as we’re concerned, if we meet a couple, then we treat them like we’re camping in their area and want to ensure the grounds are usable well after we leave – leave nothing but footprints, take nothing but pictures.  (Lots and lots of pictures, wink wink, nudge nudge.)
But even if we weren’t concerned about that, we still wouldn’t start up a relationship with someone who was concealing us from his or her other partners.  And why?
Because we think honesty, open communication, and bravery is the way to do polyamory.  And a person who’s chosen to cheat is already shown that they’re willing to lie to at least one person in a relationship in order to get their needs met.
Chances are not good that it’ll go much better for us.
“But Ferrett!” you cry.  “I’m trapped in a loveless marriage where my partner will get the house and children and my truck and my dog if I stay, and so I’m driven to cheat due to various factors!”  And yeah, there are some people in abusive relationships who can’t leave for a bunch of pretty decent reasons, and some people in alternative sexualities stranded in extremely hostile cultures, which is why I’m not quuuuuite willing to write off cheaters in general.
But regardless, a cheater has stated clearly up-front what they think of you: “You are not as important as the rest of my life.”  And of course every cheater will tell you how deeply they love you and how much you mean to them and how vital you are to them, but the fundamental truth is that when you enter into a cheating relationship, you have agreed on some level that yes, you’re not as important as all these other factors.  And that if something threatens those other factors, you can expect dishonesty.
For a one-night-stand?  That can work.  If you don’t give a shit about the person on the other side of the equation because you don’t know them, sure, I think less of you for what I consider to be a fairly sociopathic outlook, but it’s not fundamentally unwise for you to do so.
But a relationship with a cheater?  Oh, man.  What you’ve got is someone who’s already stated that they’re perfectly comfortable lying if they think it’ll get them what they need.  And they’ll tell you that no, you’re different, you’re the one they’re being honest with…
…and maybe they are.  Sometimes it works.  There’s billions of people out there, and no matter how dysfunctional it is, some group of people made it work for them.  Someone’s always going to go, “Hey, I dated a cheater and now I’ve found true love!”
And if I was saying you’d never make it work, I’d agree with you that this was a fine rebuttal.  But I’m not saying that.
I’m saying the odds aren’t good.
And if someone’s lying to their partner about their STI status, and their emotional state of mind, and what they’re doing, that’s a gun that more often that not eventually gets turned upon you.
(And that’s not even mentioning the issue that frequently arises among cheaters where they don’t see you as a person, they see you as a fantasy to be fulfilled, and sadly people treat fantasies very differently than they do living breathing human beings.  You quite often get treated like the fun new toy, which is awesome when they’re paying money to dress you up like Barbie, but then they get all confused when they pop off your arm at the socket and it turns out whoops, it doesn’t pop back in like you’re a plastic playtoy.)
So yeah.  For us, everyone’s got to be involved, or no one on our side is.  And there is a moral component to that.  But even if there wasn’t, we’d stay away because, hey.  Our business is stability.  And cheating?  Bad for business.