I LOLed at this thread and the replies. Especially entertaining was the jampi, bomoh and suspicious symbols part ^^

Sorry, I have no good suggestion...infatuation really blinds you.

If can, bribe the gangsta...if he doesn't accept means that he really loves your sis.

Be sure to record the whole process of bribing with your camera phone, so that in case he accepts, you can show it to your sis, thus proving what a jerk he is.