Please help. Advice greatly needed

My boyfriend thinks I'm cheating on him. Now he didn't tell me straight out or anything at all actually, but here's how I know: So I actually live with him and after I dropped him off at his work I came home and saw he left his cellphone. His phone don't have a password so of course it was easy to unlock. The only reason I wanted to look at his phone, was I wanted to look at his pictures. Now I know ur probably thinking tht I'm lying and I wanted go thru texts or whtever. But no I really just wanted to look at his pictures. I was hoping to maybe find some old selfies of him or something. lol I know it sounds pathetic, but I did. Well anyways, after I was done I went to swipe of the photo gallery and I saw tht he had a few other apps up (he never swipes anything off). Two of the apps were the internet and both of them say 'How to tell if your girlfriend is cheating on you'. I was devastated when I read this and TBH I really, really wish I never saw this. I really can't believe he thinks I'm cheating on him. Idk wht I did to make him think I was, but I'm not. I am not cheating on my boyfriend. I love him way to much to do that to him. What am I suppose to do? Part of me wants to confront him and talk with him about it, but if I do tht then I gotta explain I was on his phone and tht'd be kinda awkward. Does anyone have some advice? I'm really worried tht he might actually believe it and end up leaving me because of it. I'm scared. He has told me countless times tht he loves me and I believe him, but now I'm wondering if when I tell him tht I love him if he even believes me. 😓 I don't want to lose him.