If a goblin is raping your girlfriend, the first thing to understand is, is that it is not their fault. Goblins haven't learned to assimilate into our culture and laws yet, they simply don't know any better.
Ideally, you should wait until the goblin has finished raping your girlfriend, then call the police so they can come over and have a friendly talk with the goblin.
It is important that you don't press charges though. You wouldn't want to be labeled a nazi, right?
I'm sure he won't do it again after he learns his lesson.