It will never cease to amaze me when people think “they’re insecure and have trust issues. I know! I’ll just lie and hide more stuff. That’ll make them trust me more!”

Given the details, I think he’s full of shit and just manipulating the OP. But it’s something people do a lot. If someone has no qualms lying either by omission or straight to your face about something small, they’ll absolutely keep big things from you.