If you have family or friends with younger kids, try to spend some time with them! Maybe some of his fears come from lack of experience with children. I knew a friend like that - he had never even changed a diaper so it was scary!
It really gets your mind going when it could be real! I want a baby so bad but still have those thoughts every now and then!! It’s not just a little thing!! I think it’s normal to feel that way!
It’s good you’re trying to talk to him about why he’d be a good dad! maybe try exploring his fears, validate them, share your own fears and how you’re right there by him to help him through it.