Telling your W your intentions to change will likely do nothing, other than remind her of the things that she does not like about you. You need to start taking action and stop talking about the changes that you are going to make. This is a long and hard process. Even if you start to make changes and your W notices, she will still view at as you doing it to win her back. But you need to keep moving forward and make the changes for YOURSELF. The hope is that you will be in a better place, a man that only a fool would leave. Maybe your W will begin to believe that your changes are real and maybe she will make to start a new relationship with you. But you need to focus on what YOU want to change and get working on it.
