LT,

FWIW, my experience was that I was pretty much never going to feel it totally the right time to end therapy with a therapist who had crummy boundaries (and to whom I was insecurely but deeply attached). Obviously, for me, literally all control was taken away. So that sucked. But, I can absolutely see now that ending therapy was the right course of action YEARS before it actually happened. Not because S is a horrible person -- he's not -- but because the boundaries were shot, and, therefore, the therapy could NOT be effective for anything except creating an increasingly intense insecure attachment. Which meant that my brain would throw up anything and everything to prevent the therapy from ending...ever.

I'm rambling.
My point is that "maybe this is 'I want to leave to stop MC leaving me'" doesn't, from where I stand only, seem like what's going on here. I'm far more inclined to believe that that worry (the worry that that's what is happening) is popping up to slow you down in choosing to leave because you are terrified of leaving (and, trust me, I get it....leaving is painful as f***, and I'm afraid of it too).