repentance is closely associated with love. Love is the fulfillment of any requirement God has for us. If one is loving their neighbor as themselves, then they “fulfill the law.”
Owe nothing to anyone except to love one another; for he who loves his neighbor has fulfilled the law. For this, “You shall not commit adultery, You shall not murder, You shall not steal, You shall not covet,” and if there is any other commandment, it is summed up in this saying, “You shall love your neighbor as yourself.” Love does no wrong to a neighbor; therefore love is the fulfillment of the law.Romans 13:8–10
If love is the fulfillment of the Law, then sin is a failure to love. This can be through negative action or inaction. This is why Jesus equated loving God with loving one's neighbor as themself. It is impossible to love God and not love your neighbor just as it is impossible to love your neighbor and not love God. The two are inseparable.
John goes so far as to say, “Everyone who loves is born of God and knows God” (1 John 4:7).
Perhaps this is why Krister Stendahl offered this perspective on repentance:
Repentance means action in response to the pain of others.Stendahl, Krister. Paul among Jews and Gentiles and Other Essays. Minneapolis, MN: Fortress Press, 1976. Print.
If sin is a failure to love one's neighbor, then repentance is our attempt to work again any pain we have caused, explicitly or implicitly.
I hope you enjoyed his insightful quote as much as I did.