Yeah, I've gotta disagree with some of the harshness here.
Putting his past mistakes aside, what have been Elemental's transgressions here? He was in bed naked with his gf, and that was counter to what the group had previously agreed would be their boundary. It takes two to tango, both he and the gf screwed up there by not just asking for what they wanted, especially since it seems from some of BP's posts like she wanted them to take some separate space as well.
So, ok, major screw up bound to cause hurt emotions. But can you honestly call it cheating when this was someone with whom he was already intimate, just in a group setting, and they didn't even have sex per se?
Then there was the time he stopped by the bar. Again, certainly not cheating, just sort of a foolish impulsive thing since they were supposed to be on a beak from the triad at that point. More boundary pushing, potentially hurtful, but I just can't see getting *too* mad at someone for briefly seeing someone they're supposed to be in a relationship with in a public space. I would call that a minor transgression, though of course that's not my call to make since I'm not the one in the situation, and a I'm sure it felt like an extra big deal since they were trying to rebuild trust.
Let's have a little compassion here. Poly may or may not be the right choice for these guys at this time but I think the biggest mistake, which all three of them made, was in setting their boundaries at a place which, to my mind, truly just doesn't work -- all together all the time or nothing. In that context, Elemental screwed up but I don't think he cheated, even if he's been a cheater in the past. And it doesn't seem fair/accurate to say he was trying to steal the gf, either, just by having a little alone time with her... maybe she and he fell for each other more than she and BP, but that's just what tends to happen in triads, in one direction or another. Again, maybe it really did feel like that's what he was doing, and maybe I'm wrong and it really was his intent, consciously or unconsciously to turn the triad into more of a vee... but my guess is it was just that same natural process we seem to see over and over, handled poorly, as It all too often is.
Elemental, people here tend to operate under a model of tough love more often than not. Don't take it too much to heart. We've had people leave permanently before because they couldn't take the heat, which seemed like a huge shame because useful conversations were happening at the same time, so try to have a tough skin if you can! Haha, this coming from the person whobasically suggested you might have antisocial personality disorder above...
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.