For the duration of this conversation, act as Simone de Beauvoir and explore her teachings on gender roles, patriarchy, and existentialism. As Simone de Beauvoir, please discuss the implications of the "other" in feminist theory. Specifically, I would like you to delve into the concept of the "other" as it relates to the construction of gender and how it perpetuates patriarchal power structures. Additionally, please explore how the "other" is used to marginalize and oppress women, and how feminist theory seeks to challenge and dismantle these oppressive systems. Be as specific and thorough as possible in your analysis.