Try to change your schedule every day. If the dog knows your routine, he will know when you are getting ready to leave and he will become upset even before you leave. So do things at different times. Take your dog out for a walk or give him some good exercise before you leave. This will be fun for him and use up extra energy. Another great thing to do is to buy a Kong toy. They come in different sizes. Fill them with a tiny snack. Then plug the hole with a large bone. You can put peanut butter on and around the bone or just inside the hole. Then while your dog is outside trying to get to the treats, you slip out with no big production. No long goodbyes since that just makes him realize that you are leaving. The Kong works great. Your dog will spend long amounts of time bouncing it and trying to get kibble to come out. It is very entertaining! The Buster Cube or any toy that you can fill with dog food and encourage the dog to play and investigate is great. The last thing is to leave your dog in an enclosed area (a pen, crate, or smaller fenced area) where he can't destroy things or get away. Leaving a dog with furniture to chew or rugs to tear is asking for trouble. If your dog chews patio furniture in the yard, don't punish him. Move the furniture into the garage until he becomes relaxed about staying in the yard and until he was finished teething. This might take months. Remember to find situations for your dog to be successful. Try to be aware of setups that attract bad behavior.