Many times loved ones who have passed away stay around you. It is easier in the beginning for them to make themselves known through your dreams because you may not be able to perceive them him other way.
You didn't say if he loved you too. It seems he did and doesn't want to leave.
If you love him..meditate and tell him it is OK to cross over. He may perceive that you still love him deep inside and this could be holding him here.
You can meditate and see him as though he is there with you, make him life like. Tell him you are so sorry he died. Tell him anything you wish then release him.