All of the responses I've seen that talk about reasonable scenarios to use vetos could easily be categorized as common sense and/or good communication.
Veto literally means "I forbid". If something is common sensical or you're able to have a dialogue with your partner, then you're not vetoing.
I'm a pansexual female, married to and living with Indigo
(straight male), in a relationship with and living with Mr. A (straight, mono male).
One day I might stop "practicing" polyamory and just start living it!
Here Be Dragons
Originally Posted by AutumnalTone
Nobody gets a toaster oven for recruiting monos.