@Nighterfield if I had to hard guess it's that she got too wrapped into society to remember what she wanted. She forgot about herself and now regret is what remains.
If I get an letter for my 10 year old self....
I will fell scared and sorry for not using my own potential fully..... now I just another gear of society......
@Nighterfield It's extremely vague so everyone can have their own interpretation, but the theme here is about youthful dreams that never came true and are looked back in regret.