Final answer:
Roxane's main concern about de Guiche becoming commander is his increased power to coerce her into a relationship, reflecting societal norms and women's limited autonomy during that era.
Step-by-step explanation:
Roxane's main concern when she first finds out that de Guiche has been made commander of the Guards is that he will be able to force her into a relationship or marriage due to his increased power. This concern stems from the societal norms of the time, where a woman's autonomy, especially in matters of personal relationships, could be heavily influenced or overridden by those in positions of authority.
Roxane's unease highlights the lack of control women had over their own lives and the fears they harbored regarding men who could wield their power to fulfill personal desires at the expense of female agency.