the Fun dropped off the Too Much
The Fun has long since dropped off the Too Much. She’s lost the ability to lie to herself about being able to quit, or even about enjoying it, still. It no longer delimits and fills the hole. It no longer delimits the hole.
Context
The endpoint of the escalation named precisely: the pleasure has fallen away and only the "too much" remains, and even the two consoling lies — that she can quit, that she still enjoys it — have failed her. The Substance no longer even fills the hole it opened; it has stopped doing the one thing it was for, and she can no longer pretend otherwise, which is the last thing to go.