It is not so - Jonathan’s unwillingness to believe evil of his father is one of the many admirable traits in his character.
Related Commentaries of 1 Samuel 20:2
1 Samuel 20:2
2 And he said unto him, God forbid; thou shalt not die: behold, my father will do nothing either great or small, but that he will shewa it me: and why should my father hide this thing from me? it is not so.