I can relate to your situation.

Could it be that around 18-24 months you start to see the flaws in the workplace? I have experienced that with my jobs. At first, the place is new and I'm just trying to learn and getting to know people. Around that second year, you know people, their behavior, and see the problems with the place. They also know me, so it is easier to take things people do personally.

At that point, I think staying at that job takes learning to accept the people and situations 'as they are' and detaching from it personally. Instead of fighting the boss and feeling they have power over me, I respond by trying to make the situation work as best I can for me. What can I do to make this less painful for me? I also like to mentally feel like I am ready to walk out the door. And, I always keep looking for another job. It detaches me from the place in a way. It makes me feel less stuck if that makes sense.

I know your situation is different. I hope it gets better for you!