I fell out of love with my ex. He drank alot, cheated alot, had no interest in saving the marriage. After so much of this, one day my feelings for him were just gone. It was just like going numb. Funny thing was that, when I finally decided I had had enough, he suddenly decided he wanted to work at the marriage. I just kept walking....
My (second) DH is a very stubborn person and can be difficult to reason with. There have been times in the past that I have thought 'what am I doing here'!? We have also been thru some pretty rough times.....and I would say that advice given works quite well! When I felt like I wanted to leave, I just let the feeling fade and everything got better. I know there were about 2 times he thought about leaving and he got over it. If you can find a way to get through the bad times while continuing to be civil to each other so no damage is done, unless vows are broken, the marriage can get stronger!