That was it. We had to look into getting a buddy for him. So we went to the shelter and found Wheatley. He was tiny and shy, but you could tell he liked us right away and had a spark of playfulness to him.
It's taken a couple weeks for everyone to adjust, but the two dogs have really started playing together now. Wheatley, who is still a puppy at 9 months, is always the instigator.