A girl discovering letters from a deceased woman.

I read this book in high school. And I've been struggling to find it again for a re-read. This is what I recall.

- It takes place between 1800-1950s. Very rough guess. As I vaguely recall with it ending with the girl boarding a train.

- A girl finds letter from a missing/dead girl that is dedicated to her 'lover'/'beau'/object of affection.

- One scene revolves, during her birthday, the main character getting a used cookbook ( or some such nonsense ) from a boy who takes a liking her. And she struggles with the idea of simply becoming a wife and mother and nothing else.

- As she finishes the last letter she realizes that the girl who wrote the letters was likely murdered.

- There are some feminist themes mixed in. With the character fearing being stuck on the path of housewife before eventually fleeing her old home in favor of new horizons.

This is all I can really recall 15-20 years later.