How should I fix a marriage?
By keeping the faith, examining the problems and finding a viable solution.
It can only be fixed if the negative structures in a relationship are being replaced by positive ones.
Talk to your spouse about issues and be willing to change your own behaviors for the sake of the marriage.
If things are getting really bad between the two of you, seek professional help and in this case a marriage counselor who can give an objective view of the problem and offer a solutions
Stop complaining about the flaws of your spouse. Nobody is perfect. They chose you because of their flaws and hence respect their flaws and love them beyond that.
Be committed to the relationship. Both of you must take constant efforts to be responsible, caring, serving and loving. This will help any relationship from falling apart.