No, I don't think elemental was a cowboy in the poly sense. The cowboy/girl, generally speaking, would be the new third person, not one of the couple. Their gf is also not a cowgirl. There are no cowpeople in this case.
I agree that the thinking of this couple to "add" a third and expect all sex to be amongst the 3 was naive... and we constantly see that here. In fact, I made the same mistake when my ex-h and I first tried poly, with typically disastrous results, as BP knows.
But elemental and gf being in bed together naked, sex or not, while BP was supposed to be out (but came home unexpectedly) was a clear crossing of agreed upon boundaries. So was meeting gf in the bar when he was supposed to not be seeing her or communicating with her for 2 weeks. It's not huge or major, but it was still cheating, and still hurt BP. A lot.
Elemental knows he has a habit of breaking boundaries, and transgressing agreements with his primaries in the past, so even though these current transgressions were seemingly minor, they were still wrong, and still messed with BP's head.
However, yes, I applaud Elemental for coming here and "confessing" to his less than respectful patterns, and I hope this is a fresh start to more openness and honesty and eventual healthy polyamory with BP.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
There's no lying in polyamory!
I'm a 58 year old woman with 2 partners:
miss pixi, my live-in gf, 36 (together since Jan '09)
Ginger, bf, 61, married, lives nearby (together since Jan '12)