Weird about his phone?

What would a reason be for your husband to be super weird about people touching his phone? He’ll hardly let me touch it, he’s super jumpy when ANYONE touches it. Even his dad or friends. I’ve confronted him about and he just gets defensive and tells me to look through if I don’t trust him. But I still never have. I don’t want to look through it, I want to trust him. And I do, but its just starting to concern me. He says he’s “just always been like that to everyone” and he just “doesn’t like people messing with his phone.”

I know the obvious answer is cheating. The thing is, he has always kinda been like that. I just really didn’t think much of it until he was weird about me touching his phone. I never had a reason to get on it, so I didn’t. When I noticed, we got in a huge fight about a year ago. He’s still like that, but not as bad. Idk.