Dasher had severe separation anxiety. You can do small things like putting on shoes like you're going to leave, then sitting back down. Also, carrying around your car keys everywhere. Leave for short amounts of time, even if it's just five minutes. Also, when you leave, don't make a big production out of saying goodbye. Just calmly get your things and walk out. Don't pet him before you leave. I've found that giving a treat before leaving works well for Dasher. I keep him in my bedroom when I'm gone and I do make a big fuss about the treat he's getting. Now he's happy when I leave because he knows he's going to get a prized Milk Bone. I hope some of this helps. I know it's hard to ignore him like that but if you pet him and sweet talk him at that time, it only encourages the behaviour.