I changed a LOT of things about myself and for the good but a few I missed but I was not concentrating on them. I will tell you this:
If I make these changes and they stick, which based on me, I know I can do and she is the same then I will walk. No doubt about it. But I cannot until then and I hope she gives me the chance.
For you it seems and I could be wrong but...
You really don't know why she is leaving.
After 16 years and a four and half hour conversation with her best friend while my wife went to sleep I found out exactly what has been wrong all these years. That is really the bomb that was dropped on me and not when my W told me she wanted a divorce.
Let me ask you this:
Did you check in every week or every month or every day to see how she is and if her life was being fulfilled?