How do non-custodial fathers cope when they miss their kids?

I do not know the whole story here so I'm answering solely on the little info you provided. I'm a NCP and it does suck not being able to be around your kids as often as you would like. Just tell him to make the most of his time he does have and do what is necessary to get the supervised visits turned into regular visits/weekends. Again, I'm not sure the details to his restraining order so I do not know if it was warranted on hiswife's part or not.