SOLVED. Adult Fantasy, demographic unknown, classic?: Immortal character has to write down her memories. [s]

[Anomalie]

I haven't read this book, but I think it's a classic because I vaguely remember multiple pop culture references made to it (but not who made them or when, sorry).
The character had a geographical name I think, my first thought was Oklahoma but that didn't turn up results, and a major aspect was that she only had the memory of a regular human, and had to write everything down (in books?) so she wouldn't forget over her long life. That's the only thing the references mentioned so I assume it was one of the most important or noteworthy aspects of the story.
Apologies for the sparse information, I just incidentally referenced this book in a conversation because I thought it was well-known...but realized I didn't know its title, Google failed me, and now it's eating me from the inside out.
Anything helps! Thank you in advance.

[Kris]

Anomalie, around what year did you discover this book?
Is this book for adults or teens?

Story's time period(s) and location/ country?
When and where was the woman born?

[Anomalie]

I'm sorry, but I don't remember anything else about this book - I assume it was aimed at adults because I don't think teen/YA was really a "thing" when it was written, which I also don't know for sure but my instinct/vague memory tells me was likely pre-2000 and possibly quite a bit older - I feel like it might have been one of the first well-known stories about immortal characters living normal lives, since...if it was written in a time with a more saturated fantasy market I don't think it would've been as remarkable as I believe it was.

[SBC]

This is a bit of a long-shot, but it reminds me of The Crystal Singer trilogy by Anne McCaffrey. The crystal singers are very long-lived but the crystal singing affects their memories so they have to write their memories down, which is particularly important to the third book. It's a SF rather than a fantasy though. The Crystal Singer Omnibus

[Anomalie]

I FOUND THE BOOK: Orlando, which explains why I was so convinced the title character's name was a state and definitely has enough letters in common with Oklahoma that I don't feel like too much of a fool for guessing that.
SBC, thank you for your guess though, she's a favorite author of my childhood so I'll have to check it out regardless - since the book I was looking for wasn't just "pre-2000" which was my just-in-case-I'm-wrong-about-it-being-old guess but was written in the 1920s, there's a chance the Crystal Singer series picked up that idea from a grapevine Orlando planted, even.

[SBC]

Orlando makes more sense with you remembering it as a classic! I'm glad you found your book :)