I think a fair amount of people say "dominate" and are misusing the word. Dominate" sounds sooooo heavy-handed and if applied in that method to a soft dog will usually result in a dog which will exhibit avoidance behavior and perhaps when pressed too hard might bite. With a hard dog, you'll just get the bite probably.
I've dealt with this issue with my current dog as she's the domineering type, she knows who she can press, who she can herd around, who she senses some trepidation in and exploits it. Basically, she used to size up individuals and proceeded accordingly and if she can get away with her domineering crap, she would.
Two solutions I have used.
1.) For my friends and frequent visitors who have absolutely no inclination to "work" my dog, I am in charge and the dog is under my scrutiny/command/control the entire time when these guests visit and she doesn't try her "routine" with them. Your boyfriend could take this position and stop any undesirable behavior which you have described BUT solution number 2 is the real ticket.
2.) This is more pertinent to your situation. You need to take an active role in making the dog earn his resources and I mean everything as in EVERYTHING. Study up on NILIF protocol and apply it consistently regardless of the situation.
Some of my friends who are a bit intimidated by my dog and are willing to follow my instructions as to dealing with my dog have soon discovered she's not pushy once the dog realizes the individual cannot be intimidated into a position which reeks of apprehension and yielding. They simply make the dog earn any and all resources, such as attention/affection/"treats" etc. There is no confrontational moments, no power trips, no harshness, just a plain and simple learn to earn environment and the dog loves it.
Dogs aren't stupid and they know who they can bluff and bully.
jclark's advice is solid. Advanced obedience training with you actively involved will make a huge difference and I have a feeling you might be rather impressed at how your dog will cooperate. Your Mal should thrive on this type of handler/dog interaction.
I always enjoy this video and perhaps it might inspire you, it always humbles me.