Genesis 6:6 - Why should God repent?

And it repented the LORD that he had made man on the earth, and it grieved him at his heart.

Some mistake this verse to be in contradiction to Numbers 23:19 which states that God does not repent. However, God has no need to repent because he's never wrong. On the contrary, God repents because of the wrong men do. For example, God repented in making Saul king because of what Saul did (1 Samuel 15:11). God wasn't wrong for making Saul king; Saul was wrong for turning away from God.