Was in a very similar situation to you. On again, off again with a guy. He would seem to make changes like I had hoped he would make, we would get back together, he would stop trying/go back to his old ways, we would break up.

We finally got engaged. We were at different points in our professional lives and on different schedules. He would wake me up to argue with me. Arguments were always over petty things, and I barely remember most of them. It was exhausting.

It was actually on a vacation that it finally clicked for me. My role in the things he wanted to argue about wasn't as big as I had allowed him to make me think. There was nothing to be done about them. How could we be fighting on vacation, of all things?? It's vacation, we should be blissfully relaxed!! We weren't going to work.

So, we finally split for good many years ago. Things are so much better.

I doubt you'll find many people with a different story. Most of the time, changes made to get back with someone only last a little longer than it takes to get back with someone.