It does not matter if my brother/neighbor/enemy repents to me or to God or not, if I don't want anything hindering my perfect peace in Christ Jesus and my clear communication with the Lord, I must relinquish my right to myself and forgive them. Not only does that set me free from being shackled to hurt, anger & vengeance but it sets the person free whom you forgave. They no longer are indebted to you. That may not sound fair, right?
Jesus died for us while we were yet sinners and He was sinless. He took our debt away. How is that fair to Him? It may not appear to be fair, but it is the miracle of grace: unmerited favor. Unconditional love.
To forgive someone like Jesus forgives verifies that His Spirit abides in you. Jesus said on the Cross, "Father, forgive them because they don't know what they're doing."