A little back ground to help understand this reading: Shepherds had a difficult job protecting the sheep, not only from natural predators like lions or bears, but also from thieves. David and his men served as protectors for the shepherds, keeping the animals and robbers away from the flocks. And obviously they did an excellent job, no sheep were lost. In sending his men to Nabal, David was simply trying to collect what he and his men had well-earned.
David’s response to destroy Nabal and his household was wrong. It was not according to God’s will but simply a result of David’s pride. Yet God spared him from the guilt of his potential action through the wisdom of Nabal’s wife.
One final thing to point out - Just because David had multiple wives did not make it right. In every instance where there are multiple wives in the Old Testament it is a source of jealousy and division in the household. While David is called ‘a man after God’s own heart,’ he is not perfect, not even close. Yet God uses imperfect, forgiven sinners to do his will.