Not all divorces end up in knockdown dragout fights. Some end ‘amicably’.
That would be the way to hope, not the way to bet.
Czech and Slovak republics broke from each other on friendly terms, as did many of the countries once in the USSR.
If a state secedes, they will open the propaganda spigot on all broadcasting systems and declare the seceding state to be a racist Nazi bastard that needs to be exterminated.
They will then write the history to make it appear the seceding state was the most disgusting group of humans to ever exist, and it was rightful and proper that they were wiped out.
It's sort of cult like.