You might like to consider this theme by thinking about the way in which Hester and Arthur's plan to flee together, and continue their relationship, in spite of the continued existence of Hester's husband, Chillingworth, comes to naught. In a sense, even though this plan is hatched by both of them, it is important to remember that they devise it in the forest, which symbolically represents a place away from the rules and laws of men and the various restrictions that they face. It is when they return to the town, and in particular that Arthur Dimmesdale chooses to expose his own scarlet letter that they realise that their plan of living together in sin will never happen. Consider the following speech that Arthur makes to Hester as he dies:
It may be, that, when we forgot our God--when we violated our reverence each for the other's soul--it was thenceforth vain to hope that we could meet hereafter, in an everlasting and pure reunion.
Such comments point towards the impact of sin and how such acts as adultery have enternal consequences. Dimmesdale and Hester, through circumstances, manage to overcome their own particular propensity to sin and are left to face their fates.