I can only guess. I journaled my thoughts the 1st time it happened in summer of 2010. After reflection, my best guess is an increase in self-actualization. In 2010, my long term GF and I were about to become engaged when I realized I didn't want kids. The understanding of something so simple/fundamental empowered me. Around that time I became fluent. It was a glorious 90 days. The second time was almost as glorious. It happened this most recent late winter. I wasn't as fluent as the 1st time but it was still fluency and not just "good days". It also faded much faster. This time my self-actualization came about from realizing I might be polyamorous and being comfortable with it. Were these self-actualizations the reason for my fluency? I don't know. (I try not to think about it too much. Chasing it isn't good.) Other possible reasons (things that happened around both times) include increased water intake, changing my pillow, and being super depressed right before being fluent. I tried talking to some SLP friends and they just ¯\\_(ツ)_/¯. I haven't talked to anyone about my recent loss my fluency except you guys. I'm pretty sure my wife knows and doesn't have the heart to bring it up.