> I just hate that she finds it necassary to hide it. It's not like I yell at her or make her feel bad. I just want some honesty about it. When she got defensive it bothered me. We never talked about what the limit is.

It's important. It's about feelings and trust. What could be more important in an intimate relationship? Hiding things would cross a line for me. I think it did for you, and that's why you looked in her phone.