They rebelled against him, and maybe they did it paralleling the way David rebelled against God. I am not saying that we should use God's forgiveness to get away with sin. There will be consequences. Honest repentance of a PAST sin, frees you to live life fully. God erases the slate, though not instantaneously.
Some people carry severe emotional scars for years, others for months.
Pent-up hatred and bitterness, both from within and from others, slows the work of love. They try to fill a hole that one person left in their lives with another person. That puts undue pressure on the second person, and may interfere with God preparing and healing the individual before the next relationship. There are those who use scripture to claim unshakable positions on re-marriage. They give more weight to the Law than to Mercy.