Hey Wally,
How well I can identify with your situation, your feeling of frustration, confusion, perplexity, or just, "Gee, I feel like I have been used..."
I'm new to this forum, but not new to Japan and Far Eastern culture. My first experience with a Japanese gf gave me exactly the same kind of headaches as you had. Believe me, you are not alone. I think this kind of problem is very common when a man and a woman form a relationship across the East-West cultural divide.
Now, after 25+ years of association with Japanese people, I quite understand how this problem developed between you and your gf.
Also, it is not just a Japanese-American thing, but rather an East-West cultural difference. If a Taiwanese or mainland Chinese or Korean or Filipino (or Japanese) guy tells his gf, "Honey, your so sweet and I love you" the gf is likely to think he has a fever which has affected his brain.
Seriously. I have discussed this topic many times over the years with friends from all those counties I mentioned, and I can tell you with certainty that, for example, a Japanese couple married for even 40 or 50 years and never once saying "I love you" is nothing unusual. In Japan, the most treasured feelings shared between a couple are those that are expressed often and in many different ways without ever being put into words.
This is one of the subtle and beautiful aspects of Eastern culture--deep feelings being clearly expressed without uttering a single word. After living in Asia for many years, now even I find it odd the way a lot of American couples tell each other "I love you" several times a day. It now seems quite odd. But worse yet, those words may have once had meaning, but if they are overused in that way, do they not tend to become meaningless?
Wally, I hope you take all of this as constructive--including the wise counsel of the other forum members who have replied to your post.
Hope you have peace and happiness...