ve called a thousand times to tell you
I'm sorry, for everything that I've done
I think that she is telling him not to be mad at her. I think that "you never seem to be home" represents how he doesn't feel like he wants to give her a second chance or forgive her. All she wants to do is apologize, but he's locked her out.
Cavalry choirs are singing
Be my mirror, my sword and shield
My missionaries in a foreign field
For some reason I can't explain
This person is hearing all of these wonderful sounds, but he knows he cannot be a part in them. He has to be strong for the battle, whether it is emotional or physical. This person is asking the listener to be what he needs.