I don't believe that depression and anxiety, alone, can cause love to fade.

It is concerning that she's sleeping entire days away. Does she work a 3rd shift? Did she used to sleep during daytime hours when you lived nearby?

Maintaining a long distance relationship isn't for everyone. 1 year may seem like a drop in the bucket, at the same time it can feel like an eternity. Did you have major plans upon returning from your one year assignment?

I see that this is your 1st post. Hope you find the support that you need. Welcome to PC