I guess its difficult for you bf dad to have a relationship with his son when there has been so much distance and time between them. They would long ago have run out of things in common to discuss because they are so many miles apart, i am like that with my own brother to a certain extent in that when we phone each other we don't have much to say but when we get together it is easier. My guess is that his dad is visiting the brother becuase his having a new baby is a good excuse to do so and will be an ice breaker/distraction and something for them all to focus on. If there has ever been a fall out between them then i have no doubt that dad is very much looking for ward to seeing your brother but you know what guys are, all stubborn and don't say what they are feeling. They will all appear frosty on the outside when they really want to give each other big hugs and kisses. All you can do is be there for your boyfriend, don't slag his dad off and try to break the ice between them, his dad is probably feeling just the same way you bf is feeling