A Very Basic Misunderstanding

I realize, too late, that we have failed to understand something important. I've tried to pinpoint the exact moment of misunderstanding, but cannot. Nor am I able to discern the exact nature of this failure of understanding. I know only that it was important that we not fail. In this failure there was a decisive moment, that I cannot recall, when your heart hardened against mine and there is no going back. For us it was a point of no return. Don't worry. You can blame it all on me.