Since you get it in the first part I don't see why you get it this afternoon. I don't like him yelling at you though. Does he not have a passcode? Can you not use find-my-phone on a computer (oh wait, you can't use that either...). But I don't get what the root of his privacy need is, you two seem to live together. What if something happens to one of you, bah nvm. How long have you been together?

You both should apologize to each other. If you guys have a rule, treat it as a rule. Maybe encourage him to put a passcode on and if you need to find your phone you only use it to call by using voice "Hey Siri call gf..." "Google call gf..." - without unlocking.

I think it's a stupid rule, IMO. Just for me, I don't care if my wife checks every bit of my phone out because I would want the same rights as her. We use each other's interchangeably, guess we are old with nothing to hide. Having said that, even though we know each other's passcode, it's smart to have a passcode makes a phone almost-useless if stolen.