[mmt]

I'm not sure it's what you intended.. but here's my stab at what you're getting at.

The key is that forgiveness is primarily about (and, arguably, for the benefit of) the emotional state of the one granting the forgiveness.

It can be granted independent of any feelings of guilt (which are impossible to know for sure) on the part of the recipient.

Similarly, someone else's happiness about my birthday is irrelevant to me if I don't care about that someone, no matter how genuine that happiness is.