What is the ruling on my fiancée working as a pharmacist in a mixed pharmacy (men and women) where another female employee is available, given that I am able to provide for her and she refuses to stay at home?

The work of a woman who adheres to the Sharia-compliant dress code and avoids private seclusion (khalwa) with non-mahram men is permissible. However, private seclusion with a non-mahram man is forbidden. If her work involves several men, then khalwa is negated, even if she is with two men, provided that temptation is not feared. Forbidden mixing (ikhtilat) is the gathering of men and women without adherence to Sharia guidelines. As for a mere gathering of the two genders under one roof with adherence to Sharia guidelines, there is no harm in it, provided the woman observes hijab, is modest in her interactions and speech, and lowers her gaze.