Your partner is definitely not communicating or acting in a way that indicates she has the skills to balance a poly relationship.
Also, she did not exercise patience in exploring her other relationship and in affect betrayed your trust.
Are you running away? Not from my perspective. Is she caught up in NRE or perhaps not as poly as she thinks? Probably.
Think of the long term when deciding what to do. Is this something that will be worth it or healthy for you in the long run?
Playing the Game of Life with Monopoly rules.
Monogamy might just be in my genes
Poly Events All Over