I learned the wonderful truth of what it means to live in a right relationship with God as my loving, heavenly Father, and I responded by opening my heart to Christ, receiving him as Lord and Savior, and dedicating my life to God. Those experiences have stayed with me the rest of my life, and I have never seriously doubted God's salvation and forgiveness. Yes, and on a regular basis. But not in order to be forgiven. I live in a constant relationship of forgiveness.
Confession is rather a part of a nurturing, strengthening, and healing process.
Failure to confess could lead to hardness of heart and indifference to sin. It could eventually disrupt and even break that relationship. In addition, there could be occasions of gross transgression and wrong doing when I would need to seek a very special pardon from God, or a time of estrangement when I need to seek a renewed restoration and reconciliation. The analogy of a human relationship can be helpful. My wife and I have a very close relationship, one of trust and harmony.