Thirty Letters in Thirty Days

I've realised, I know, why I've drifted away from you, and yet I can't help feeling a little sorry about it. We used to be the closest friends- I hung out with you all the time, did almost everything at school with you, and a few things outside of school- but now we don't even talk, don't even recognise each others' existence. It's a little weird compared to how we used to be.