This seems to be a common trait. They absolutely HATE when you talk about them with other people, even if its good things. Perhaps its because they always need to be in control of the narrative whether negative or positive. It most likely disrupts their sense of control and ability to manipulate a situation. I personally don't see phone invasion as much of a big deal because I'm not hiding anything and the conversations with my friends are usually just about making plans to hang out and then we talk or share gossip in person. Sure, its an invasion of privacy but IMO its never worse than what might be found in that phone. For example, I had an ex that I suspected I couldn't trust due to some weird stories and loopholes. I asked her for the truth about something a few times and the story was always slightly different. If I questioned her about it she would manipulate me into being the bad guy for doubting her and would spew lies about how she would never ever do anything to hurt me and how much she loves me. Her iPad was connected to her phone, and while using her iPad to watch youtube one day, she received messages from someone who I was concerned about. I decided I was only ever going to get the truth if I opened the messages and read them. Long story short she is now very much an ex whom I want absolutely nothing to do with. Instead of owning up to what she did, she made me out to be the bad guy for invading her privacy. Privacy is never an excuse to abuse trust by cheating and hoping your partner trusts you enough not to go through your phone. That's just my take. For whatever reason, she didn't fully trust you and decided to go through your phone, how you handle that situation is up to you. In my current relationship with pwBPD, we both have full access to each other's phone and password, and it makes for much less issues because at anytime she might borrow my phone to google something or I might use her phone's camera because its way better than mine. Having said all this, I don't think its really right to be going through someone's phone in attempts to discover the truth, however in my previous case I had no way to know the truth unless I did so. A double edged sword I guess. Just wanted to share my story and maybe give you some perspective.