Is it permissible for a wife to work in a city 40 km away, given concerns about mixing (with men) and being far from home, especially since she is not in financial need and feels bored due to her husband's frequent absence?

What we advise is for the wife to remain in her home and utilize her free time in beneficial matters, such as reading the Qur'an and religious books, attending scholarly gatherings, and listening to useful audio lectures, in order to avoid the corrupting influences and dangers of mixed-gender work environments.