I had written, "... nous étions partis" in lieu of the recommended, "... nous étions parties". I don't understand the recommendation:
So "étions" as auxiliary "être" in imperfect (indicative) tense, 1st person plural, added to the past participle "parti" so as to construct the compound past perfect tense.
I constructed the past particle as male gender plural so, "partis". This as we have two assumed female genders (Joséphine and the writer Amélie) as well as at least one other, gender unknown, as expressed through the larger sentence, "... et avec laquelle nous étions parties".
I thought the rule for French grammar was, choose the male gender when the gender is unknown...l don't want to support patriarchy. I do want to get my grammar straight. Thanks!