You're in good company.
"If there be any among us who would wish to dissolve the Union or to change its republican form, let them stand undisturbed as monuments of the safety with which error of opinion may be tolerated where reason is left free to combat it."
Thomas Jefferson, 1st inaugural address, 1801.
Read the entire Declaration of Secession Independence, and Amendment 10 of our Constitution.
If that's not enough follow that by the ratification debates of the states (especially New York and Virginia). Add The Kentucky and Virginia Resolutions. Which state(s) threatened secession repeatedly long before the South left the Union?
For bonus points, read the Texas v White decision, and the argument for indissolvable nation. Justice Chase based his decision against secession on the word "perpetual" in the Articles of Confederation, so for extra credit, in Article XIII of the Articles of Confederation, how many states had to agree to dissolve the union (hint: last line of first paragraph)? Compare that with Article VII of the Constitution (remember, there were 13 states at the time), "The ratification of the conventions of nine states, shall be sufficient for the establishment of this Constitution between the states so ratifying the same." Was nine more or less that the number agreed to in the AoC?