I'd say so if we talk about personal relationships when people are, sometimes, made of such different materials that it's incompatible.

I don't see therapy failure as a relationship failure. If the therapist is not a good match, that should be obvious from the beginning and you just wouldn't stay with them. But if the work went on for some time and there was progress and then the progress stopped, then, to me, it means that the therapist came to their natural limitations and it's time to close this chapter and to move on to something different.