I get the feeling Balthazar that you are being asked in some way to remain positive and I really feel that asking your Guardian Angel for protection for both yourself and your fiance would be of great benefit. As you are an atheist, I do not wish to convince your good self of anything but one thing I will say is that everything happens for a reason.

It seems perfectly logical to myself that this is happening in order to allow yourself and your girlfriend to ask for angelic protection. I am certain that were you to do this, your girlfriend will begin to recover immediately. You do not really have to change any of your beliefs apart from to acknowledge that you have a Guardian Angel. Everyone has one.