[DoodleDawg]

Slavery had nothing to do with the reason NC and other slave-holding border states left the VOLUNTARY union of states.

If one state can leave the union at any time, for any reason, without any discussion with the other states then can the other states expel one state at any time, for any reason, without any discussions with the expelled state? If not, why not?

[DiogenesLamp]

If one state can leave the union at any time, for any reason, without any discussion with the other states then can the other states expel one state at any time, for any reason, without any discussions with the expelled state?

Yes.

Freedom of association also requires freedom of disassociation.