What does Psalm 32:3 mean?

David tried to keep his sin of adultery secret (2 Samuel 11:2–5). After learning Bathsheba was pregnant, he brought Uriah, her husband and a soldier, home from the battle zone. David assumed she and her husband would have intercourse and everyone would assume that the husband was the father of the unborn child. But the plan didn't work (2 Samuel 11:6–13). Later, David gave orders to move Uriah to the frontline, arranging for him to be killed in battle (1 Samuel 11:14–15). He then took Bathsheba as his own wife.

For some time after, David continued to deny and ignore his sin, but his failure to repent and confess caused him physical distress. In ancient Hebrew thinking, the bones were the most essential essence of a person's physical body. For the bones to "waste away" implied intense sickness. The Lord was chastening him. Sin has consequences. In David's case, it brought emotional and physical pain. Although not all sickness is the result of sinning, a believer may become weak if he refuses to repent. Paul wrote that some Corinthians were weak and sickly because they partook of the Lord's Supper in an unworthy manner (1 Corinthians 11:27–30).

It was not until Nathan, a prophet, directly confronted David that he finally broke down and repented (2 Samuel 12:1–15). This inspired David to write Psalm 51.