Ps 3 O LORD my God, if I have done this and there is guilt on my hands-
4 if I have done evil to him who is at peace with me or without cause have robbed my foe-
5 then let my enemy pursue and overtake me;let him trample my life to the ground
and make me sleep in the dust. Selah

Sin is a capital offense before God. But in this life some sins do not bring us trouble in comparison to other sins. Some of the consequences of sin can be with us our entire lives. The Psalmist teaches that the lasting consequences of sin is related to our covenants. Solomon warns about the sin that spreads to the streets. Covenants involve two people.David teaches that the way to avoid the a major downfall of His kingdom was to keep his covenants.The law, curses, statutes, promises and decrees live and die on the covenant.Because a covenant is a promise that God would fulfill the axioms. The reason that David spoke the curses was to remind himself that the covenant oaths are life and death promises. The daily curses were reminders that the king must keep his military, political and marriage covenants in order to keep the kingdom. Just like God swears to His own hurt if He breaks the covenant so the king swears to his own hurt. We can commit a lot of sins that do not bring lasting problems. But when we break our covenants we can never recover in this life.

There were two ways in the account of Davids that were deserting the fellow solders in war, and taking personal vengeance in peace time. David was not like Saul. He enforced the capital punishment without a question. This is the one sin that enraged the king. But when David committed adultery and murder it was the chief act of hypocrisy that has ever been recorded in the Bible. Because David spoke the law, covenants, curses, etc more than any other king in the history of Israel. This is why God singled out David as doing everything that God wanted. God called David His king. Breaking a covenant resulted in life time consequences to David. A covenant involves other people.

You could make an argument that Davids sin was worse than the apostle who ravaged the church. This is why king wrote Psalm 51 as a public confession of his capital offenses.Psalm 51 was written many years after the incident. It was also a document alerting the people that God did not reject the king. If God had given David what he desirved then who could replace him? He had accomplished more than any other king in the history of Israel. God would not destroy the kingdom in applying His justice.
Covenant faithfulness is centered on the teaching of the curses.God curses those who come in their own righteousness. The wicked curse the righteous. The wicked curse is an attempt to violate the covenant. We always say that a man is known by his actions. But with God our promises in covenant carries more weight than most of our sinful actions. So God curses those who are not implanted with his word and seek to redefine it. His redefinition is breaking the covenant. The entire culture and kingdom depends upon a man keeping his promises in a covenant. This is why our words can bring us a life of trouble. The king pronounces life and death curses in order to expel  the covenant breakers who are not implanted with Gods word..