Honest disagreement is often a good sign of progress.
No matter how close we are to another person, few human relationships are as free from strife, disagreement, and frustration as is the relationship you have with a good dog. Few human beings give of themselves to another as a dog gives of itself. I also suspect that we cherish dogs because their unblemished souls make us wish - consciously or unconsciously - that we were as innocent as they are, and make us yearn for a place where innocence is universal and where the meanness, the betrayals, and the cruelties of this world are unknown.
Marriage isn't a love affair. It isn't even a honeymoon. It's a job. A long hard job, at which both partners have to work, harder than they've worked at anything in their lives before. If it's a good marriage, it changes, it evolves, but it does on getting better. I've seen it with my own mother and father. But a bad marriage can dissolve in a welter of resentment and acrimony. I've seen that, too, in my own miserable and disastrous attempt at making another person happy. And it's never one person's fault. It's the sum total of a thousand little irritations, disagreements, idiotic details that in a sound alliance would simply be disregarded, or forgotten in the healing act of making love. Divorce isn't a cure, it's a surgical operation, even if there are no children to consider.