Sorry you are going through this. She does sound somewhat addicted to NRE and you definitely do not sound healthy in this. If you really want to be monogamous, feel normal, and that you are not surpressing her, I think you should do what is best for your personal health.
You are young, no kids and have lots of time. Perhaps it is best to find some one more suited to how you love. Immediate short term pain now instead of possible long term, roller coaster of pain in the future? Can you really imagine going through this for the rest of your life with her?
Take care of yourself the same way she is taking car of herself.
Best of luck.
Playing the Game of Life with Monopoly rules.
Monogamy might just be in my genes
Poly Events All Over