That is a little bit odd. Even when I called immigration previously about our break up they even told me they don't really care about it because my Visa isn't affected by it and I can even reapply for it for another 5 years without him due to the Visa rules.
you are in Australia and:
you hold a subclass 461 visa, or you are not the holder of a substantive visa and the last substantive visa you held was a subclass 461 visa
you are no longer a member of the family unit of a person in relation to whom you were granted a subclass 461 visa
you have not become a member of the family unit of any other person
I fit all the above criterias and not sure about the situation with your friend but it does sound weird especially if they are still together and she applied for it for a 3rd time. Maybe she was asked for proof because they are still together just to be precise and have everything on file.
I am really scared in general just because it takes so long for everyone and your life is on hold and you can't make any big decisions without knowing what will happen next.