Is it forbidden for a woman to imagine other stories while having intercourse with her husband, and by doing so, does she forbid what Allah has made lawful and permit what He has made unlawful?

Scholars have explicitly stated that it is impermissible for either spouse to imagine another person during intercourse. It appears that a woman imagining a man she previously rejected falls under this prohibition, as it resembles what is unlawful. Therefore, strive to rid yourself of this unhealthy behavior.