Amelia Earhart knew what she wanted, and what she wanted was love, independence, and possibly a piece on the side.
Earhart first expresses some trepidation about getting married at all ("You must know again my reluctance to marry…") for fear of derailing her career, which "means most" to her. Maybe it's just me, but this kind of agonizing over work-life balance sounds like a distinctly familiar dilemma to the modern feminist. Earhart goes on to give the rough outline of an open marriage ("I shall not hold you to any midaeval [sic] code of faithfulness" and emphasizes rather than monogamy a goal of "finding happiness together", on which she finds the marriage to be contingent.
Sounds like Earhart was a progressive woman who faced many of the same issues that ladies in love face today. This modern life!