Why does my dog leave home?

I have a four year old shiba inu which I love to death. He's always been mine since he was born, and Ive always treated him very well and trained him to be a good respectable puppy. Never hit him, fed him good dog food (purina one) play with him all the time. and he's always been a great dog til recently me and my dad moved to the country and now I let him roam the countryside instead of keeping him on a leash for walks which he loves. at first it was cool he got to go outside when he wants I didn't have to walk him but now he stays gone all the time? he doesn't even eat at home anymore.. ill let him out at 7 am and wont see him again til 8 or 9 pm? I don't like how much he's gone any idea why he stays gone so much now?