The short version of Veto context, purpose and some shortfalls can be found on Xeromag's Poly Dictionary.
Thanks for this, it answered my question.
You want to do X
I'm uncomfortable with that. I tell you why. It may involve safety etc. I may have insight you are not aware of. YOU may have info I am not aware of.
One we have all the facts in front of us so both are at the same level - you still choose to do X
I lose respect for you, our relationship and may develop real concerns about your judgment.
You proceed to do X against my recommendation
It turns out well
I learn something, about myself, about your judgment etc.
I'm big enough to admit I was mistaken, have learned something, and we become closer
No power dynamics required.
This. Very much this. Thanks GS!
I'll take the possibility of fucking up a relationship of mine by crossing a boundary rather than the CERTAIN possibility that I'll destroy it by assuming I have any claim over my partner's choices.