Obviously some of the Northern States cared. They made the practice of slavery illegal in their states. Something that most of the Southern States never considered.
But this is very misleading. Modern people think the northern states abolished slavery because they thought it was immoral and because it was unfair to black people.
A very tiny minority of the Northern public was against slavery because they thought it was immoral. The vast majority of them hated slavery because they saw it as an economic threat to their own wages and income, and also because they hated the idea of associating with black people.
The Northern peoples didn't actually like black people. The "Land of Lincoln" passed all sorts of laws making it illegal for black people to live in Illinois, as well as various other horrible laws regarding how they were treated in that state. Other Northern states did likewise.
To assert that Northern people cared about black people is one of the biggest lies of the Civil War. The vast majority hated them and wanted them kept out of the nation. In fact, much opposition to slavery was based solely on the desire to not have black people in their communities.
So when you say they "cared", don't mislead people as to what it was they actually cared about. What they didn't care about was the misery and suffering of black people. That is a later day fabrication used to justify what the Northern people did to the Southern people.