I have a lot of issues with paranoia, and not just small things but big things. I think the one big thing about paranoia is you need to learn reality checking. Being able to step back and say "is this possible or not." Reality checking can be extremely hard because with things like paranoia you often also have what is called lack of insight. So, things appear perfectly logical to you, but it's actually not.

My husband helps me a lot with my reality checking. Perhaps it is frustrating, but if he's paranoid about phone calls, you can let him know who is on the phone. Caller ID and such. The other direction, he may not be hiding anything from you. But, yes, paranoia can go that way to. Perhaps he thinks people are after him.

My advice is to be transparant with him. Show him you're trustworthy constantly, but keep track of his paranoia. If he is acting paranoid about you personally or it gets worse (starts talking about things like people being after him, bugging his phone, etc,) that's something that needs to be adressed with his doctor.