"failure"

I want to ask if anybody deals with the same feeling as me. When i sit down to write and spend hours on something, and in the moment really thinks i have created something decently, and then take a break and tries to start on the music behind it and continue on it. I usually get hit with a sense of failure because it isen't as good as i first thought, i guess i get in a state of "delusion" when im in the zone writing and therefore write some .... interesting stuff. Anybody that can relate? and if so maybe knows how to bypass this. Thank you in advance :D