You two seem to be good people, but not the best match. I agree this is a really good time for self-reflection and to analyze the things that make you happy. Its equally important to understand the role you played in the breakdown as well as figuring out exactly what you wanted/needed from him. I swear by the Love Languages book! Its a really short read and allows for some powerful insight on your wants/needs along with your potential partners. Though you are removed from that relationship now, I bet you would learn what your previous partner needed. The complaint "nothing is ever good enough" is normally said by someone who wants to hear that they are appreciated. He probably needed more words of affirmation to feel valued/loved.
Regardless, breakups suck and the loneliness is cold. I hope the mourning phase passes quickly and you meet someone new in 2020!