Well, I get your drift but it's not always as simple as that for people. I think there's shades of grey on the subject although not fifty...
The vow is to be faithful to your spouse. I completely agree that people can fall out of love or even get to the point at where regardless of love, the relationship is toxic. However, the only person I can speak for is myself in stating that I would not allow myself to go outside of my standards due to my emotional state. Two wrongs don't make a right.