One of the main situations that occasioned the writing of 2 Corinthians seems to have been the sinful behaviour of one individual who had, in the past, caused grief and difficulty to the whole church and to Paul.

It seems that at first the church had been slow or unwilling to discipline the man in question and that Paul had to encourage (and insist) that they did so. 2:6 suggests that factions had formed around the person and issue in question. The majority understood the need to discipline the person, but a minority didn't and stood with the offender. 

Eventually, however, formal church discipline was brought to bear. Though the letter isn't clear what form this took, it is obvious that the man has repented (v7-8; 7:9-12). But now a different situation has arisen. Where previously the church had been too slow to discipline, now it seems they are being too slow to forgive and restore. It seems from v6 that some are wrongly suggesting that the punishment hasn't yet been severe enough.

The result is that a repentant man is being refused reconciliation and is in danger of being overwhelmed with unnecessarily excessive sorrow and grief because some are unwilling to renew fellowship and affirm their love for him.

How easy it is for this to happen in a church when there is a heated atmosphere of grief caused by sin. How many times have I heard something along the lines of "they offended against me in the past, so there is no way I am going to relate to them with openness in the future in case they do it again." Obviously there are situations where past hurts call for an ring fencing to prevent reoccurance. Paul is not suggesting, for example, that a victim of child abuse may forgive their abuser, that they should simply ignore what happened in the past and leave themselves vulnerable to them again. But this isn't that situation. This is a church refusing to fellowship with a genuinely repentant person because they won't put aside their grief over what he did previously.

The fact that they won't demonstrates that, at the time of writing, they haven't forgiven the person, and they must. It is essential for the health of the church. Paul goes so far as to say that one of Satan's schemes is to prevent people being forgiving and thereby to destroy churches (and church effectiveness) by driving wedges between Christians (2:11).

I can think of two situations at the moment in which church leaders are being urged to comfort and restore an individual to fellowship. In one situation the person is genuinely repentant for hurt caused. They clearly fall into the 2 Cor 2 category. In the other, the person has offended in ways that most people in the church are unaware of (and can't be made aware of), and is unrepentant. Part of their church understandably think, therefore, that the individual falls into the 2 Cor 2 category and (perfectly reasonably) cannot grasp why reconciliation and restoration remains incomplete. This presents a very difficult situation for the church leaders.  

2 Cor seems clear that restoration, forgiveness, comfort and love is the appropriate response to repentance. It should be offered as quickly as possible, in order not to give Satan a foothold. It isn't the appropriate response to non-repentance. In that situation what gives Satan a foothold is declining to discipline and allowing an unrepentant person to continue in their sinful behaviour towards a church.