Letter writing day

Today, I'm in the mood of letter writing. Wrote 4 letters to different people at one go. They are important people in my life. One I've known her for 24 years (haha easy guess yea?). Two I've known them for 10 years (will be meeting one of them tomorrow) and the last one is someone whom I'll be with for the rest of my life (easy guess too). Can you tell which is for who? Hahaha