This is lovely, and heartbreaking. I particularly like the way in which the informed reader can see Yaz making the mistakes that so many have before her (The Doctor's line about recklessness made me think of Clara, but it could be others) and gradually realizing that she's doing it, without being able to stop. "Nobody tries to catch her and there’s nothing to break her fall" , indeed.
You always seem to know the Doctor, and you know so much about humans; that's why your writing is always so good. Thank you for writing this story, even if it's got sharp edges. Perhaps because it's got sharp edges.