I guess it is somewhat true....teaching a human can certainly be more challenging than teaching a dog.
Your dog has the two of you sized up about perfectly it seems...they are pretty smart and observant.
I guess there should be no mystery as to why the dog does not heed your boyfriend's commands....the stage has been set already....he lets your pup do mostly whatever he wants to do. Of course, you can change this but obviously your boyfriend has to commit to the program as well.
I'd say your pup just has one personality....and part of it is...he's a good read on human characteristics.
I have a feeling you already know the answer to this situation since you have earned your pup's respect and position.