Possibly some separation anxiety when you walk away.... wanting to keep his pack together. Maybe your boyfriend is more calm when he walks him?? If my wife and I walk the dog and one of us walks away our dog gets very anxious but gets over it in a few minutes as her attention is turned to other things and/or she realizes she can't change the situation. I am more calm than my wife and the dog responds to that by being more calm. But if I start acting nutty, she will too, she kind of adopts the mood we set.