Love prospers when a fault is forgiven, but dwelling on it separates close friends. (Proverbs 17:9 NLT)
Ask any couple that's been happily married for very many years and they'll tell you about the importance of forgiveness. It's inevitable in any relationship/friendship that offenses will occur and if you allow them to fester they will drive you apart. "Love prospers" where people live in the present and let go of the past (hurts).