I have asked my T about what he will do if I tell him I'm quitting. I told him sometimes therapy is just too hard and I want to flee. He said he will tell a client why he feels termination is a bad idea, but leaves the decision up to the client (obviously). He will also call at some point within a few weeks to follow up with the client and be sure he or she is okay and knows that the door is open if he or she wishes to return. He said he continues to think about clients after they termination and would like to know they are okay.

ETA: my point was, sometimes it can be reassuring to just TELL the T that you're thinking of quitting and why, and get some clarity as to what happens and what to expect if you really do ever say you are quitting.