I think you're right about the added complexity of co mingling of relationship styles and the tendency to second guess how everyone "must " be feeling or thinking from years of societal programing ....jokes about sloppy seconds and the like.
I don't however think that its a given that by you being second in line in a similar situation would automatically dissolve the problem. It could reenforce your opinion or belief. You may hate it and never be OK with it. Which is fine. And this would goes to your point about how you see things...your truth.