One of the most important methods or mantras to use when exploring poly is to go at the speed that everyone is comfortable.
This means regular discussions, and conscious decisions about how to proceed. It's sounding like you folks don't have that - you need to.
Have you worked out some boundaries, like about whether you get to meet each other's partners, etc?
What are the areas that she now wants privacy for? Is it about sexual details, or just about who she is dating?
"Listen, or your tongue will make you deaf." - Native American Proverb