Like others have said, of course it's "allowed." And inevitable. I think what's more important is, if the T makes a simple mistake (a misattunement, or saying "the wrong thing,") they acknowledge it and make an attempt to repair the therapeutic relationship with an apology, discussion, and/or an explanation. This can actually be a good experience in the end; I have had some of my most healing moments in therapy after those kinds of mistakes.

If it's a major ethical or therapeutic violation, there needs to be a much more in-depth and serious examination of their motives and process. Those situations can be truly damaging, especially if there is no effort on the part of the T to rectify and take responsibility.

We as clients need to remember that therapists are human. In relational therapy, where the "therapeutic alliance" is paramount, they have to rely on training, education, intuition, our feedback, body language, guesswork...this is not an easy job. It involves trying to be "good enough" for someone who is already carrying pain and wounds, whose perceptions and interpretations of the world around them may be heavily distorted, in a time when that client's life may very well depend on the therapist doing all the right things. This does not excuse incompetence or damaging behavior, but under ordinary circumstances, should inform how strongly we react to our therapist's errors. None of us is entitled to perfection.