You should watch Turner and Hooch. You may look at your canine friend a little differently after that.
If all else fails, I suggest doing what canine/wolf species do. Get on top of it and hump it to show your dominance. LOL
Leave dark chocolate on the kitchen counter with the intention of eating it later, then leave the house. When you come back... at least you didn't do it on purpose.
of course this problem cannot be solved unless we know how hot your girlfriend is. Have to understand whether you should put up with such a problem like this dog.