[SamiNFurbabies]

Does someone see him mid-day to take him out or play with him?
How is he potty trained?
It's good that you walk him before you leave... I would continue doing that.
Izze used to hate me leaving her at home---now she is excited because that means she'll get a bonemarrow milkbone cookie and a small bit of swiss cheese.
It's good that you leave the tv on and provide treats--- does he have a crate that he can feel secure? I kennel Chachi and Suzie... I leave a dog bag open for Molly (and she stays there all day)... Izze hates crates(she's a rescue 3x rehomed, came from a puppymill or shady breeder so it is understandable), but the others love it and it's a nice place where they can feel secure and relax. I would close the kennel until he feels comfortable.
He could have separation anxiety---but that doesn't mean it can't be worked out. All four of mine had it at one time and they are all better now. I don't think that you'll rehome him You love him too much.
Just try to be patient.
I must say that it helps that I have multiple.