Brother in law of girlfriend threatening my father

I love a girl,, she loves me. She has no father and lives with her mom , elder sis and her jija. It is a reted house. Jija is agent sort of employed, meagerly paid. We fear that he wants to marry her off to his friend. My gf doesnt want to marry and wants to make a career first. I also have started my career just 1 month ago so am not in a position to marry. We both r 24 yrs old. What should she do? She loves me, her mom is ok with it but her jiju is creating problems for us. Today he called up my dad and threatened him that if he sees us together again, he will get us married then and there. He has some source in police. Please help sir. What should we do to stay on the safe side even if he takes such an action?