OP on a related note I also see your girlfriend indulging in 'amae' which is probably an alien concept in Australia and to you and has you baffled over her behavior once she is back in Japan and behaves like a spoilt kid with no regard for your feelings. Amae is a sense of self indulgence where she acts like a child and relies on you 'forgiving her behavior in the same way that a child gets away with murder but will still be loved by her parents.
Some of it is cultural IMO and behavior that you find difficult to reconcile with what you saw in Australia. Maybe its that she is just being herself in Japan, it was in Australia that she changed and you cant handle seeing the real person she has become.
More info on amae here