second hand smoke is worse for dogs and cats because their lungs are so much smaller then ours. Its like smoking around an infant. Also, the smell gets in their coat and its very hard to get out. I groom a couple dogs that come from smoker homes and honestly its disgusting. The poor dogs stink and I've tried everything to get the smell out. They also have a "smokers cough". One of the dogs even as breath that smells like smoke. Dogs can get sick and get lung cancer from second hand smoke, just like people. Ask your BF if he would smoke around an infant, and then tell him that's what he's doing when he smokes around small pets.
Even when you smoke outside the smell lingers on your clothes and then you transfer it to your dogs when you pick them up and cuddle with them. Not good.
Secondhand Smoke Is A Health Threat To Pets MCLEAN ANIMAL HOSPITAL