opinion about obeying rules

The theme that arises as a consequence of the plot is to love people well and to honor one's commitments. These are the values or virtues that would have spared the characters in this story from their tragic demise that ends up killing the traitors (Florence and Edward both kill themselves).

This is a negative way of showing the value of love and keeping one's word. The book seems to be a warning against those who would casually cheat on their spouses instead of working through the intimacy issues together as a couple. Edward and Florence both destroyed their marriages by having commitment issues; they were not willing to sacrifice their desires for the betterment of their relationships.