I suppose that is what happened to me this fall with a series of life crises. My reaction was to withdraw, but that's my usual reaction to extreme stressors, so of course I withdrew from my therapists as well. The relationships suddenly felt different - I felt even less need for them than usual (and usually I just see them as a necessary evil). And I was much more aware not of the power to leave - I was always aware of that - but of a willingness to do so. The more stuff came down the pipe and hit me, the more I was willing to tell everyone and anyone to go stuff themselves. But I would not be surprised to learn that my reaction is atypical.

I am not willing to say categorically that any client power is merely theoretical and can easily be outmaneuvered by the therapist, because that is not my experience in therapy or in life, but I see how it could indeed be some clients' experience.