This person also posted an amazing, unvarnished update recently (about 5-6 years later): https://livingafi.com/2021/03/17/the-2021-early-retirement-u...
I can relate to the anxiety and ennui they experienced in 2018. Something good about being in the rat race is that even during bad days you don't feel adrift or wasteful. During the first couple of months after I quit working, and after moving abroad, I hadn't yet enrolled in full-time language classes. At first it was easy to enjoy myself meeting new people, going rock climbing, traveling a bit, going on dates, etc. But after a while, I started noticing that if I woke up at 11am and didn't have "something to do," i.e. a plan, I started feeling a very strong sense of unease, something like a very mild sense of panic or alarm. Like here I am with no work to eat up my day, plenty of money, nothing but free time. If I wake up on the wrong side of the bed, or just don't feel like I'm enjoying myself, I am utterly wasting my precious time on Earth. That's a pretty dark chasm lurking just beneath the surface. If I'm having a bad day but can still pour a cup of coffee and go to work, I'm at least banking up money for some future day that I can enjoy it.
I feel like he was a little unfair in how he characterized his partner's experience of that ennui, although I don't blame him for feeling bitter after an affair. I've never wanted to keep up with the Joneses or spend my life jockeying for status, but I still don't think I'd feel okay permanently quitting work this young. There's more existential dread in being immediately responsible for enjoying every single day to the fullest than I'm ready to face.