(((BelleCat)))
I'm sorry that your friend has left you alone. I have been there too.

There is no easy or pain-free way to go through this time, unfortunately. You can correct yourself, whenever you start going out of the "normal" boundaries.
It wasn't Nathan's "job" to be there for you through thick and thin, every single day. He's like everyone else in the world. He gets tired of hearing complaints and woes, and sometimes wants things to be a little lighter or happier. He may have had a time or two where he really needed to get things off his mind, but he felt that it wasn't a good time (or match) to share these things with you.
I'm not trying to make you feel bad, just trying to help you see Nathan's side of things a little better. Hopefully, you'll be able to repair your friendship in some time and take these things into serious account when you do so ~ in order to make it a true friendship.
I have already lost my friends...they're
LONG gone. I wish that I could contact them and become friends again, but it's too late in those cases. I've tried a few times to contact each of my old close friends, with kind gestures, apologies, but not one reciprocated.
Please do think about my experience and opinion carefully. I wish you the very best ~ gentle hugs to you!