I think of vetoes more as ultimatums, in a 'this shit doesn't fly by me anymore - take it or leave it' kinda way, but I see that is not what people generally mean by the concept. Of course, if I had been married for ten years and just now starting to play the field, I might be more inclined to try to work on a veto policy when getting into poly.
What do you think of temporary vetoes, as in 'I love this person but they need to work their shit out before we can continue as metamours, because right now it's having too much of an impact on our family life'?
"Resentment destroys more alcoholics than anything else. From it stems the root of our spiritual disease."
"In dealing with resentments, we set them on paper - list people, institutions and principles with whom you are angry. Ask yourself why you are angry."
"In most cases it was found out that our self-esteem, our pocketbooks, our ambitions, our personal relationships, including sex, were hurt or threatened. We were sore, burnt-up." Alcoholics Anonymous, 64-65.