He was always ambivalent about abolition. Not a fan of slavery, sure. Maybe. But he made it clear over and over and over again that he would much rather keep the country together than free any slaves if he could.
He also MANY times said he wouldn’t even know where freed slaves fit into American society, proposing they be shipped off to some island to colonize so he wouldn’t have to deal with them.
It was only at the insistence of his generals that it was a military necessity or they’d lose the war that he freed some of the slaves.