Hello Dinghui! The antonym of "affect" is "unaffected" The prefix "dis-" could be read as a "reversal", and the word "affect" in "disaffect" comes from the word "affection". So the meaning of "disaffect" is closer to "dislike" or to not be loyal or affectionate to someone anymore.

If it simply isn't, I'm not sure what sort of a response you would want. .