Hi its could just be that he wants to spend his time off with his other half, since they both work, I'd say its a boy thing. I'd just let him know when your visiting the others and say if your not busy it would be great to see you, but if not thats fine. I think it sometimes takes them to become parents themselves before they grow up and want to spend time with family. There is always one in the family that wants to go it alone, he knows you are there when he needs you. Just accept it and enjoy being a granny, its great. Your now a glamorous gran.