These are women married to men who represent the power of society, and the control of sporadic situation. Moreover, the women, as their wives, are paradoxically meant to represent the exact opposite: The co-dependence, the neediness, and the feebleness of the "weaker sex". However, we know that Susan Glaspell's purpose in "Trifles" is to expose the double standards of society in terms of the social expectations placed upon women.
Hence, Mrs. Peters and Mrs. Hale have the task of breaking free from the expectation that they are meant to remain quiet, idle, and useless through the investigation. In addition to this, they now have a responsibility to report the abuse that a fellow female has obviously suffered by the hand of her husband. However, all this becomes nullified when we see how, with their disclosure, there may be consequences: First, the victimized wife will have a "motif" to have killed her husband, no matter how well-justified it may seem. Second, she will inevitably land in jail. Third, there will be no way to secure her future.
Therefore, Mrs. Peters and Mrs. Hale are between the sword and the wall and there is no possible winners in their situation.