Commentators explain that God's question, "Shalt thou build me a house?" is a rhetorical way of saying "no." This wasn't a sign of displeasure, as God still affectionately calls David "my servant." The reason, revealed later in 1 Chronicles, was that David, as a man of war who had shed blood, was not the fitting person to build a temple for the God of peace. That holy task was reserved for his son.