Analyzing the facts you gave me:
1) Her parents would never approve of you; does that mean she will never introduce you?
2) Not being introduced is eating you up inside; do you want to continue being eaten up inside?
Based on your answer to these questions, you have to decide if this is the scenario you want for your life. If not, you don't have to continue with her. It seems that she wants you for reasons other than marriage.
Don't you think that you deserve someone who loves you for who you are? Don't you think you can attract a woman who will be proud to introduce you to her parents? Get a grip. You can do better.