Words. How they are meant, how they are interpreted. For example, the word "manipulative" can be meant as an attack -- or it can be meant as an attempt to simply describe something accurately. It can signify that the one who uses the word is unhappy. (Though I think there must be a better choice of words since it is so easy to see it as an attack.) In any case, if there is a discontinuity between how words are meant and how they are seen, only more discussion can resolve the mismatch. And if the person who is more trained cannot work through this, then the therapy is in trouble. JMO.