What would you do?

Me and my boyfriend have a pretty open relationship in terms of like our phones and facebooks and stuff. Well, we fought the other day and I brought up that he is always in my phone but never lets me have his. And when I do get his it looks like he has deleted texts and Facebook messages. Last night he was sitting next to me and went to get in his phone and I noticed he changed his pass code, that pissed me off. But I didn't say anything I just removed his finger prints from my phone and changed mine too. I don't know what to do anymore, I trust him, but sometimes I get insecure and like to be able to check. Now him doing that has killed my trust all together. What would you do?