Is her boyfriend from here.. or are they over here for a few months, sort of backpacking around?

If they're just over for a few months then I'd just keep the deposit.. however, if they're based over here permanently then I'd give it back as they might have a network of friends that could cause aggro. From car being key'd to really nasty stuff like shit on your doorstep or fire pingpong balls from her snatch at you etc....


Cheers,
Grant