There are a few questions that keep popping up in my head as I listen to you sitch. First, is the feeling of not being in control of the sitch causing you to feel angry which is making you want to through in the towel.
Second, do you feel his changes are genuine or not. Could it be a sitch where he is trying to force you to leave so that he won't have to pay as much support. This would also make you look like the problem, saving face for him. Could it be that his heart is in the right place, but he just doesn't feel overly motivated. Maybe he feels that you want it more than him and therefore can set his own time and effort level.
What is tough for me right now is that I don't see things changing the way/rate I want them to, however, there are positive changes heading in the right direction. It seems right now we are waiting for changes of heart and commitment to these changes. I have decide that I'm not going to jerpordize my future due to lack of patience on my part. If you can still feel love for that man, perhaps you need to show that love in the form of patience.
With that said, may I say that perhaps some of my problem is due to impatience and imposing of expectations on others. Perhaps it is time for both of us to evaluate how much this affects our sitchs, along with how much we need to change. A few months ago Poepad was forcing me to think about what I did wrong in the sitch. Although my W never said I did much wrong, I have come to realize some things like this were present. Even though our spouses usually brought the problem into view, I don't think any of us have the right to "cast the first stone".
Well enough from me. Work on yourself and fix your own problems (that's my mantra these days). Your changes will result in changes from him/her. Have a better day and keep posting.