I don't know you, but you sound like you're burned out. So, I hope that taking a break from gamedev helps you re-center and feel better. And, I'm biased towards gamedev (of course... This is gamedev.net), so I hope after you've had some time, I hope you come back.

Take care of yourself.

Maybe you're not happy with the things that you're writing. I remember a few weeks ago you've posted a 1 header library for some OS dependent stuff (windows/threading/fileIO/...). And I'm sorry if I put you down, even if it is a tiny bit, with my comments, that wasn't my intention at all.  Otherwise if you weren't happy writing these kind of things you maybe should do it some other way. 

A while ago I had a "pride", that really prevented my to do the thing I want, just because couldn't swallow the fact and I didn't wrote everything. Maybe I still have this problem (and I'm certain that for some things I still do), but I'n my case I really did not want to use any 3rd party libraries for my game @home.

I really wanted to write a rendering API(a warpper around D3D GL ect.) - and I did
I really wanted to write a shading language(that gets translated to HLSL/GLSL) and I did
I really do not like SDL and i wanted to write a window abstaction API - and I did

I do this at home after work and it was and still is very time consuming. I surely learned a lot while writing these, and I'm kind of happy with the right now, but during that period I had that pride fight.

After that I needed a UI for game in game editing stuff, and I really wanted to write a UI library. After a few days I kindof managed to swallow my pride, and just use Dear ImGui. I like that the library is there and easy to set up, but I do not like the API and I do not like the coding style, but I kind of convinced myself because other on the interned proved to me that the lib is stable and sufficient, so I swallow my pride and started using it, and kind of lying to me that one day I will write one.

The next thing in the same fashion as the UI, was the physics and collision. at 1st I wrote something that wasn't physics based at all (it was that thing that the player is a sphere/ellipsoid and you slide it against a triangle soup) but it wasn't that flexible. So I started looking at how to write a physics engine. again I had a fight with myself and I agreed with my otherself that I should use bullet physics - yes it has bugs, yes the API is kind of strange, but I had to keep the work going, after all I wasn't sure if my game is suitable for physics, and I had to test it as soon as possible. (I will write a physics thing one day).

The next thing is the level editor, now about that... well I kind of wrote one, It isn't completed yet I believe that I can make it pretty usable. I'm kind of justifying it with ;
"I want my game to have a level editor for the players"
"I can make tools that help me edit the world faster".
So this is kind of justified and I have to admit it is really fun, I'm really interested in DCC.

I'm not sure if I communicated my point, but in my head I've got two persons I call them (for this example, because I know you are familiar with these people):
- The Muratori guy - that guy is usually angry (at least this is my image for him...) and want to write everything by himself
- The reasonable inexperienced wanna be a gamedev - who just wants to see a game going.

The true "me" where I;m subconsciously happy, Is somewhere in between, but I'm not sure where, because I forced my mind to bend around some ideas, that some of them are mine, some of them are taken directly form someone else that I think (or all other people think) are smart.

I'm kindof finding my way out of this situation, but it took me a lot of pride swallowing(and it still takes some...) to make me happy with the things I do.

Maybe in your case it is not the physics engine, the UI or the level editor, maybe it is something else.
If this is not the reason why you're unhappy, I wish you to find the real reason why and overcome it!