They are sovereign
Show me the phrase or words in the constitution that says a state can secede from union. The states agreed to a union when they rejected the articles of confederation and adopted the constitution in 1787. This issue was settled in 1865. Of course I’m serious. If you think you can have a country where any state can leave and set up an independent country because some nuts in the state legislature decided they’re being oppressed, then you have some serious faults in logic. What does the word union mean to you? The idea that individual states can secede (and supposedly rejoin) willy-nilly is preposterous. PREPOSTEROUS!!! How’s that for being serious.