Understanding your Japanese girlfriend can be very difficult, but not impossible. Probably one of the hardest things for Western men is catching those “non-verbal” cues that she sends out almost constantly.
The one that Japanese women use quite often is not really a non-verbal cue, but instead is not talking at all. This is a little different than the Western woman’s “I’m not talking to you because I’m mad at you” but rather “You won’t try to see things my way so I’ll just be quiet and deal with it.”
Japanese women (and Japanese people in general) prefer to quietly deal with bad situations rather than to verbalize their disapproval. This works in arguments as well. For example:
Japanese girlfriend: “I do it this way.”
Exasperated you: “But I do it this way.”
Japanese girlfriend: “You don’t understand me!”
Exasperated you: “I do understand you! I just think that we should do it my way.”
Japanese girlfriend: “Oh… Okay…” (Silence)
Now, she will most likely not bother to fight anymore. She will stop talking and become very quiet. It’s not the “steaming-mad” quiet of some Western women, but an almost sweet and overly polite quiet. It may look like you won the battle, but in fact she is just dealing with the bad situation and hasn’t changed her opinion at all.
Remember, calm politeness in Japan is one way of distancing oneself from others. If your girlfriend is acting very polite and not warm and loving, she is actually putting up a barrier between the two of you.