He has checked out. Unless and until he decides he wants to stay, there is absolutely nothing that you can do. You really do not have any control over his decision, but that does not mean you cannot influence it. Until such time as he is willing to check into the relationship - it is heading in the direction of separation.

I am curious on one comment you made - you mentioned that you took off your ring and left. That you really hurt him. The comment you made that I question is that you said you have tried not to do that again. Was that in reference to hurting him or taking off your ring and leaving?

I checked out of my marriage years ago because I was miserable (your husband saying he is unhappy is probably a huge understatement). It was not until I had a series of long and painful conversations with my wife were we at the point that I thought about staying. It was a series of weeks where her behavior changed and I saw series change happening with her that I decided to be fully invested. I am glad I did, because we are much better now than we were before having some issues.

IMO, you have zero to lose to have a series of long and hard conversations with him on what needs to change. If that change is acceptable to both of you - you both have to be committed to it, and working on it. (If you have had them already and he still wants a divorce, you are heading there). If either of you are not committed to change - you are done. I am very sorry.

You asked specific questions - He has had a rough year and has not seen the change that he needed - for him, that is enough time. He is not making a rash decision, he has been thinking about this and living through this for half your marriage. After I checked out, I went a year or two without arguing with my wife - I did not acre enough to argue with her. Do not take that you did not argue as everything being okay. Only when I had enough did I start to argue again.

My situation is different than yours. I have kids. I was thinking about divorce everyday. I also remember the exact moment where I decided I had to try one last time. My wife was in a mood (I suspect something like what your husband calls complaining). I was eating lunch or dinner with my son and looked at him and realized I could not leave my children with her because she was ranting about something insignificant to me. Thing is, my wife and I both had things to work on and to be better together. We sat down and developed ways to work on things. We were committed to changing things.

While I might have already said this - talk to him, develop a mutually agreed plan on what needs to change (both of you) and start implementing it. If you don't, you have no chance.

Good luck.