Could be mental, could be your caloric restriction (1400 is low as hell). Could be both. I'm 34 and haven't deloaded in over a year. Take a week or two off? Yeah, on vacation or being sick. Deload? No.
Yah, i hear you for sure. I am trying not to do what i did last time, which was chasing new prs and ultimately getting nowhere on my true goal, which is the fat loss. I really just want a flat stomach, but i want to get it while not losing any muscle, which is why i'm doing 5/3/1. That is why i feel like the deload week isn't a big deal at this time. Once i have hit my goal, my intention is to get really, really strong, while maintaining a very low bf%. I never want to be fat again, so i need to get thin first, then really get to work then. I know for a lot of people its all about really being strong, but being so obese for so long, i just want to get to that point where i'm thin.
I suspect i'll be able to eat 3k+ calories and lift heavy on keto fully adapted and get some really damn good results. But that is all speculation till i get there.