Jesus is Essential
Matthew 18:15: Moreover if your brother sins against you, go and tell him his fault between you and him alone. If he hears you, you have gained your brother.
If he sins against you, you are to go to him. This verse is speaking of sin committed by a believer. The obligation is upon the one who has been injured to approach his brother who has offended him. 1
Walking with Jesus
When your heart has been broken over the sinful behavior of another believer, you must go, you must explain the fault, and you must pray for a repentant response. Do not assume anything. Instead, take the initiative with the hopes of gaining a friendship back.
Brethren, if a man is overtaken in any trespass, you who are spiritual restore such a one in a spirit of gentleness, considering yourself lest you also be tempted. Galatians 6:1
True restoration first takes place before His cross, then before others.
Praying
Lord, thank You for sending Your Spirit to confront me. I have sinned against You. Thank You for restoring me.
1. 1McGee, J. V. (1991). Thru the Bible commentary: The Gospels (Matthew 14-28) (electronic ed., Vol. 35). Nashville: Thomas Nelson.