For those who use Numbers 23:19 as a prooftext that God does not change:
Num 23:19 “God is not a man, that He should lie, Nor a son of man, that He should repent. Has He said, and will He not do? Or has He spoken, and will He not make it good?
Would we not do better to understand Balaam’s (a prophet despised in the Bible) description of God as limited to the context and Jonah’s description (that repentance is a core of God’s very nature) of God as absolute?
Jon 4:2 So he prayed to the LORD, and said, “Ah, LORD, was not this what I said when I was still in my country? Therefore I fled previously to Tarshish; for I know that You are a gracious and merciful God, slow to anger and abundant in lovingkindness, One who relents from doing harm.
God is Open 
Is Jonah more loved by God then Balaam? Both aren’t the most faithful of God’s prophets. I think Moses or Isaiah would be better examples.
That is true. But in Jonah’s case, the text is showing Jonah is bitter against God because he knows God’s true character, character testified in the narrative.