Paul Explains His Reasons For What He Has Done And Calls For Leniency On The One Who Had Sinned And Has Now Repented (2 Corinthians 1:23 to 2 Corinthians 2:11).
Paul now explains why he had changed his travel plans after his hurtful visit and then explains the subsequent severe letter he had had to send to them. Both these events had seemingly happened after he had written 1 Corinthians. And then he gives further instructions because of how great had been the effect of his severe letter. He did not want anything to be taken too far.
In 1 Corinthians, while he had had to rebuke, it had been in expectation of things being put right without too much difficulty, so that he had not anticipated that it would put a barrier in the way of his visiting them for a goodly period. But when he had subsequently paid them a quick visit it had turned out to be a very hurtful one, for someone had raised the church up in opposition against him, so much so that he had felt it best to leave Corinth immediately and deal with the matter by a severe and strong letter, rather than by having an open and possibly permanently damaging confrontation.
What the further trouble was is open to interpretation. What seems clear is that one person was mainly behind it all (2 Corinthians 1:5-7), and that somehow he had managed temporarily to get a good proportion of the church (or of one particular house church which Paul visited) on his side. The result was that when Paul had made his surprise visit to Corinth, that person, supported by other members of the church, had made hurtful and spiteful accusations against him, presumably with ‘here, here' being heard in the background along with a lot of scowling faces, and had roused so much ill feeling that Paul had felt it best to withdraw quickly in order to preserve the peace and unity of the church.
The accusations presumably included the fact of his supposed fickleness in not visiting them when he had promised to, probably stirred up by clever manipulation, and possibly included the fact that now he had come it was only for a quick visit, and not the long stay he had promised. The suggestion was therefore probably made that it demonstrated that he was both unreliable and dishonest. This might have especially affected those who had seen themselves as the primary targets of 1 Corinthians.
The main person who had opposed him might well have been someone who was concerned to gain pre-eminence, and had won some adherents, and did not want Paul's interference. Possibly it was he, along with some of those who saw themselves as super-spiritual, who stressed that Paul's weakness, and appearance, and sufferings, demonstrated that he was not really an Apostle of God. But even the less antagonistic members might well have been upset that now that he had come he had said that it was only for a short visit, and thus have joined in the dissatisfaction against Paul.
A less sensitive Apostle might, after consideration of what was happening, have remained so as to demonstrate that his authority could not be questioned, without having regard for the long term effects, concerned more for their own reputation than the food of the church. But Paul was not like that. He was not concerned about his hurt pride, or his position for its own sake. All he took into account was the long term benefit of the church. And he had therefore immediately left Corinth because he had felt that that could not be achieved at this time by harsh personal action, or fighting his corner in person, leaving long term hurt all round. He had recognised that it must be dealt with in another way. Present feeling was running too high.
At which point he had sent a severe letter, the severe letter which he will now refer to, which turned out to be so successful that he has to advise leniency towards the person involved.