If I'm in a relationship and start feeling the need to snoop through his stuff, I know it's time to break up with him for my own benefit. Even if he hasn't done anything. If its at that stage, I clearly don't trust him and insecurity like that almost only gets worse, never better. Snooping rarely stops one from being insecure when nothing is found, it just encourages someone to snoop harder.
I don't see how anybody could stay with a person they had to snoop on. I was in that relationship once, and I hated the person I was during that whole time after I caught him cheating on me. You find something, you're upset. You don't find something, you're still insecure and searching. Sick cycle of being mentally fucked no matter the outcome.
I learned that I could only be with someone I trust completely for sure, more for me than bc it'd be tucked up to them.