Is the unintentional viewing of pornographic clips and images in novels, TV series, and social media considered a violation of an oath, which stipulates a three-day fast whenever such clips are viewed, and does this include stories and books that contain similar situations?

If the oath was uttered under the influence of waswasa (insinuating whisperings from Satan), then it is not binding, and no expiation is required. However, if it was by the free choice of the one who swore the oath, then she does not break it unless she intentionally views what she swore to avoid. She does not break the oath by reading what was mentioned, nor by viewing something that does not contain the scenes she swore to avoid. If she sees something unintentionally and then immediately lowers her gaze, she does not break the oath. Breaking the oath only occurs through intentional viewing. One must beware of waswasa and avoid succumbing to it.