Read the Ordinance of Sucession for each state. The preservation of slavery is the primary reason given.
That keeps getting trotted out, and it is completely misleading. Only a few of the 11 states secession conventions issued such statements, and other statements that speak more to the real economic causes such as this one, are simply ignored because they don't fit the narrative that the Northern History book publishers prefer.
Also ignored is the fact that Lincoln repeated on several occasions his support for protecting slavery if the South would simply remain in the Union.
Since Lincoln had offered them all the slavery they could possibly want if they just remained in the Union, how can we say they wanted to leave because they wanted to protect slavery?
You are repeating propaganda created by the victors in an effort to justify the bloodshed for what they did. There was no intention of abolishing slavery for nearly two years into the war.