It could be either:
CPTSD - From Surviving to Thriving by Pete Walker // Trapped in the Mirror by Elan Golomb // Recovery: A Guide for Adult Children of Alcoholics by Bowden (and colleagues) //
Though now that I'm trying hard to remember which one it could have been I'm not even certain it really was one of those. Maybe it was more of an aggregated insight that I gathered from studying the subject. Either way those books can shed a lot of light on unexplainable mental blocks we have.
It's certainly in Pressfields book. He calls it 'resistance' and swears its at its strongest when you're near the finish line. That's a good observation but he doesn't go into why that could be. Those other books offer explanations to connect the dots. At least for me.