John Chrysostom
The word "again" shows that the Apostle had already been grieved by the Corinthians. While he seems to defend himself before them, he imperceptibly rebukes them. Consider how great the Apostle's sorrow must have been, if they had already grieved him once and were ready to grieve him again. Yet he does not say to them directly, "You grieved me." He lets them understand it by other words, saying, "I did not come to you so as not to grieve you." This is equivalent to what I have said, but it was more acceptable and easier to bear.