As a certified separation anxiety trainer, the way I help dogs feel better about their people leaving is by very gently, over time – and based on the individual dog’s behavior and body language – help them feel safe about being alone at all and then helping them feel better about the things that predict that (now safe) alone time. I use extremely careful systematic desensitization to the entire picture of humans leaving a dog alone which includes things like keys, locking the door, putting on shoes, and the actual duration of the alone time.