If you have committed an offense against someone else, even if you have already paid them whatever monetary damages you owe, you don’t get forgiveness from Above until you’ve asked your victim to forgive you. The Mishnah (Bava Kamma 8:7) derives this principle from the story of Abraham and Avimelekh; after Avimelekh has taken Abraham’s wife for himself (after that whole “she is my sister” thing, which we won’t go into here), God tells Avimelekh (Genesis 20:7), “now, return the wife of that woman, because he is a prophet, and he will pray for you.”
A commentary on the Shulkhan `Arukh (Me’irat `Einim, Choshen Mishpat 422:1) takes this argument a step further. You shouldn’t just get your victim to forgive you — you should patch up your relationship with your victim to the point where he or she would be willing to pray on your behalf.
May you all be inscribed and sealed for a happy and prosperous year.