It is said, that when we forgive others, as Jesus commanded, we do it in love, we don't take into account a wrong suffered (1Co 13:5), hence it is regardless of the presence of repentence from others. Consequently reformers like John Calvin categorize forgiveness in two ways, both enjoying a genuine forgiveness though of different judgments for each account (Calvin Commentary on Matthew 18:21-35).
But do we say that we are not God, hence we cannot "choose" who to forgive? Are we better than God for being able to forgive even the unrepentant? It is then logical to ask of the relationship of God's mercy as compared to the image we reflect of Him. I shall rather say, it stands to reason that if God forgives those who are not yet repentant, then we mustn't restrict our forgiveness to only those who have repented their offences.
Then what about predestination? Of those, the only ones whom God personally elected since the foundation of the cosmos, for salvation, to be His children? Are we completely restricted to understand this mystery? How could it be revealed to us while forbidding us the understanding of it? Thus it stands to reason that predestination or the doctrine of election is not "the secret things" of God (Deu 29:29) but if there be any misconception, it is only due to our own culpability.
I propose therefore, that this right of election, is parallel to when a bridegroom receives his bride. Favoritism? Definitely. Respecter of person based on her conditions? Only where God permits since there is no respecter of persons with God (Romans 2:11). Infallible decision? Well, we're but mortal, sinful men.