There is a concept of willpower fatigue. I'm not sure how much I buy into it. It does sound like what happened here with you and what seems to happen with me and my eating issues. How you describe SH is pretty much how I describe my binge eating behaviors; cycles and all.

My T tries to get me to see that I am doing the best I can at any given moment to cope. I think it's her way to try to get me to shift away from the guilt and self negativity that comes as part of the cycle.