Force of arms is one way, sure. That’s how every political entity comes into being.
The idea is that states couldn’t enter the union on their own, they had to apply and receive permission with conditions. So, the argument goes, they should leave the same way. Right or wrong, there is some logic there.
“Right or wrong, there is some logic there.”
Bad logic. Keeping a state in the union against its will is a violation of the principle of self-governance, which undermines the very legitimacy of the nation itself. If they don’t have the right to leave, then we never had the right to separate from England, and we are still a bunch of illegitimate rebels.