There are definitely “event driven” DOWs separate from the normal AI DOW math.
For example, I had a couple pop ups events that triggered a war between myself and the founder of a different faith. In the first, I was given the choice to convert or die, but my ruler had some trump card stat that let me pick a middle ground choice. A few years later though, a similar one popped up with no out. This was with a country that was militarily weaker and with which I had “pleased relations”