This ignores things like slave catchers who ventured avoid state borders into the north to catch free men (illegally) and the south by seceding was taking hostage those people and other Americans. West Virginia exists because the government of Virginia decided they wanted to secede but the people didn’t

Also states don’t get to vote on laws and just leave and get their way anyways if the vote doesn’t go their way. That’s the agreement they made, and the only basis they had for seceding was they feared a law that would make them unable to own slaves.

The confederacy also started the war with the north by attacking fort Sumter