I've had lovers who put on a "poly" hat when it was convenient; to me a poly arrangement is negotiated and consensual and discussed before or during the relationship, not just a handy excuse to whip out when you've been caught with your hand in the cookie jar. I've had lovers who cheated and then tried to convince me that what I saw wasn't what I actually saw -- shame on ME for being fooled into believing their lies. I've had lovers who, after breaking up, they ended up with someone else in less than a week and called them their "one and only"; it did little to convince me that it wasn't going on behind my back before the breakup occurred (I only hoped the new "one" hadn't also been fooled, but that wasn't my karma to bear). I've had lovers who cheated in ways large and small but without the actual sexual activity that would typify "true cheating" but they were still forms of infidelity. It's a loss of faith in the heart. It undermines the relationship and kills it slowly instead of by sudden cardiac arrest. Someone already said it -- "What she'll do WITH you, she'll do TO you" and it comes back to bite them eventually, but for my own sake and like Softness, I don't pray for karma. I pray for healing for myself and for them. And like Gemme said, it does real long-term damage to people. And like Apocalipstic said, whether it's the cheater or the one they're cheating with, they're both culpable and both are sewn of the same cloth, IMO. It's just as likely to happen in their brand spankin' new "true love."
What I've found to be sadly true is that when someone lives for the thrill of craving constant attention and adoration, they don't care who they hurt while they chase after that. They have a bottomless pit of need. Their hearts go from 60 to zero in nothing flat, instead of the other way around -- which is the opposite of how true love develops. Deliberateness of ill intent is a love-killer, not the ending of an honest effort where people failed to meet in the middle. We all make mistakes, and things don't always work out. But if someone tries to destroy my life, who can allow that? Me. So I've developed a zero tolerance for staying involved with a cheater, it just doesn't work for me. Might work for others, c'est la vie. I do prefer monogamy because I'm just too old to keep up with poly
I'll take a shot in the dark and say that every one of those cheaters called ME "psycho" after we were done. Why? Because I didn't fall for their bullshit? When I called them on it, they were afraid I might ruin their game somehow. It's not up to me to reduce the victim pool, though. Their best defense was a good offense. But I don't need to behave that way. Though I do have to say, I was uncomfortable sitting around taking it in the shorts non-consensually by people who were supposed to be out of my life, but all I could do was maintain my own composure -- and keep a pair of tight boxers on.
The funny thing is, I have a low ratio of lovers to years on this earth -- haven't I learned anything yet about recognizing a boundariless person? That's my issue today, if I knew how to start a thread it's on my mind. Sorry to be so long-winded, my mind doesn't know how to build sentences any more that aren't at least 40 words apiece.