Need help with a jealous bf?

okay, so my best friend has SERIOUS jealousy issues and whenever we go out to the movies i have to actually put in effort to make it look like im not AT ALL interested in ehr boyfriend, and even if she catches me near him without her, she flips out and goes into ***** overdrive. any suggestions. i've tried talking to her but its like talking to a brick wall. it's gotten so bad that now i can't even recieve a piece of gum from her boyfriend if he offers because she'll think were screwing behind her back. its BS!