We approach the issue of termination from a co-evolutionary perspective, as though therapy is an unspoken contract between two parties which can be broken at short notice by either party. When the family comes for help or is sent by another person, we assume they want to be rid of the unhappiness and conflict which they experience, but they also want to preserve the integrity of their meaning system and the relationships built around it.
The therapist is in a similar position; he or she wants to help the family change, but also wants to preserve his own meaning system, as demonstrated in ethical values, economic use of time, outcome considerations, etc. Termination will occur when either party begins to feel there is no longer a problem, or that the problem will not be solved with this approach, or that the continuation of the therapy poses a threat to the integrity of the respective meaning systems. We continue working with families until they report that there is an improvement in the symptomatic behaviour or (more likely in our experience) until they say the behaviour is no longer a 'problem' for them.
It is consistent with our model that we disconnect ourselves when we begin to see evidence that the family is thinking and