Jonathan loved David, covenanted with him, and predicted that he would be the second in David's kingdom when David would be the king (18:1-4; 19:1-7; 20:8, 14-17, 41-42; 23:16-18). Saul's intention was to preserve the kingdom for Jonathan. However, Jonathan was not willing to take the kingdom but recognized that David should be on the throne. Jonathan should have told his father about this and then should have left his father to be with David. In typology, for Jonathan to follow David would have signified our following Christ today and our giving Him the preeminence. If Jonathan had gone with David, Saul might not have suffered such a tragic ending. Saul might have been helped by Jonathan not to build up a monarchy for himself but to build up the kingdom of God.
Jonathan realized that David would be the king, but instead of going to follow David, Jonathan stayed with his father because of his natural affection toward his father.
Because Jonathan would not leave his father, he suffered the same fate as his father and died with him in the battle.
Jonathan lost the proper and adequate enjoyment of his portion in the good land promised by God because of his failure in not following David according to God's will due to his natural affection toward his father.