The sentence you provided appears to be somewhat complex and abstract. It seems to be discussing the concept of the "unlived life" and how certain characteristics or identities (in this case, being gay and being the "Odd Woman") might be used as a basis for grievances or complaints. Let's break it down: "Our subject is the unlived life": This suggests that the topic or focus of the discussion is the life that hasn't been lived, perhaps referring to missed opportunities or unfulfilled potential. "The question for each of us": This indicates that there is a question posed to each individual. "Would we have manufactured the inequity had one not been there, ready-made": Here, it seems to suggest that the speaker is pondering whether they would have created or fabricated a sense of unfairness or inequality if a certain condition or characteristic (such as being gay) hadn't existed as a pre-existing factor. "he is gay, I am the Odd Woman": This part of the sentence provides specific examples of the conditions or characteristics being discussed. "He is gay" and "I am the Odd Woman" are the identities being referred to. "for our grievances to make use of": This suggests that these identities might serve as a basis for grievances or complaints. In simpler terms, the sentence is exploring whether individuals would have found reasons to feel aggrieved or treated unfairly if certain characteristics (like being gay or being the "Odd Woman") hadn't already existed as readily available factors to attribute their grievances to. It's a contemplation on how we might use certain aspects of our identities or circumstances as a basis for complaints or dissatisfaction in our lives.

I think the author is saying something like, "when you complain about inequity, be certain that you are complaining about real problems caused by it, rather than just using small differences to invent an excuse."