My girlfriend will get left and right mixed up which makes me upset.
I see. Is she the only one who gets left and right mixed up?
She's not great with directions.
Try to be understanding when it comes to her not being great with directions. It would probably mean a lot to her if you were patient with her in these circumstances.
I don't give a shit about her terrible directions.
Well yes, do not allow it to be a big deal. She is not doing this on purpose to be hurtful.