Trust

I currently live with my boyfriend, He has trust issues for no reason on my part. I’ve always had a passcode on my phone, he’s known the code, a few months ago he decided to snoop in my phone while I was asleep. I felt very upset, there was nothing to hide, but the way he went about it. Then anytime we would get into an argument he would try to take my phone for validation he could trust me. Wrong. I never snooped once so once day after he got a new phone I went thru it and found he was still texting/entertaining other women. Nothing serious but still wrong for the first few months of our relationship. He constantly is accusing me. So one night during an argument I changed my passcode and now he’s so bothered I won’t give it to him? Am I wrong? I’m just tried of being accused of someone I am not. I’ve tried to explain with or without a passcode he needs to work on his trust issues but he is only focused on my passcode accusing me of hiding things.