Well first there were no “negotiations” leading to the insurrection. Seven states announced that they had seceded before Lincoln assumed office.
The north went to war to save the union and won freedom for the slaves in the process. The south went to war to protect slavery and lost everything in the process.
You are correct there were no “negotiations” leading up to secession, which was unilateral by each state.
There were, however, multiple attempts by various groups to scramble around and craft a compromise that would end the crisis, as had happened in 1820 and 1850, among other years when sectional crises erupted.
Among those attempts there was a Peace Conference and the Crittenden Compromises.
There was even a Corwin Amendment to the Constitution that would forever protect slavery from interference by the federal government within states. The Amendment passed Congress and was sent to the states for ratification. Lincoln expressed no opposition to the ratification of this amendment, though the President has no role in amending the Constitution.
No the states joined the union voluntarily and wanted out. They would have had to make economic adjustments because owning slaves is wrong and dealing in human flesh is despicable. The central government forced them to stay. Very dictator-like.
States have rights recognized in the our founding documents. Fedgov has enumerated powers. This fight is far from over.