Independence training.
Training our dogs is fantastic, however, the reinforcer commonly tends to come from us, the human. When our dogs have a separation related distress or when we are trying to prevent one from developing, we want to teach our dogs that things will be okay if they are away from us, and the reinforcement for this behaviour should ideally come from the dogs environment so they see value in that separation.
Tether a Kong to the leg of a table, or chair using some rope. Stuff it with treats of very high value such as wet food, loaf, peanut butter, cheese, ham, chicken, etc.
Show your dog the tethered Kong and then move quietly into another room engaging in a quiet activity such as reading, watching tv, etc.
Your dog is now required to choose whether or not they would prefer to sit with you, or move into the room that holds the valuable Kong. If your dog chooses to eat from the Kong, this is reinforcing them being away from you.
Dogβs are unlikely to achieve this on the first few goes, so try it routinely.