we must not be merely willing to forgive, but eager to forgive, once the offender expresses a desire to make things right.
Keep in mind that we're not discussing a case of a personality conflict or some other disagreement; we're talking a case of one Christian sinning against another. Under such circumstances, the offended party is under no obligation to repent. We're not to bear grudges or wish them ill - we're to pray for them in the hope that they will come to repentance so that they relationship will be restored. However, if the person who sins against you refuses to repent, Jesus clearly instructs us as to what we should do in Matthew 18. First, we should reason with the other party, personally. We shouldn't involve others or crank up the rumor mill. It could be that it's just a misunderstanding that can be worked out between the two of you and, if so, it should go no further. If not, then we are to approach the person with two or three witnesses so that the facts can be confirmed. If the person still cannot be won over, he is to be taken before the church. If that extreme effort fails, then he is to be disfellowshipped.
Simply saying, "I forgive you" and moving on without holding that person to account only increases the likelihood that the behavior will be repeated. Finally, this entire process is not an act of malice or vengeance; it's an act of love with the aim of getting a brother to see the error of his ways and make things right. If the offended party sees it any other way, then he has issues of his own to contend with.