There was of course the option of respecting the self-determination of the Southern people, especially considering it was no different then that exercised in the 1770s.
But Lincoln couldn’t get that because he was hellbent on power and couldn’t stand the thought that anyone didn’t want to be under his benevolent rule.
In the 1770s the American people had no representation in the British government. In contrast the southern people had pretty much controlled the American government from 1800 until Lincoln’s election.
Then the Slavers threw a hissy fit and provoked a war which cost 600,000 lives. They destroyed their homeland over their addiction to slavery. Smart boys.