>>12
Well then I think you don't even need to ask what the problem is. I am sure that her parents' misgivings are grounded in 'religious' beliefs (which don't seem very good or conducive to love).
I'm not a christian myself but am fairly well versed in the bible, and I note that jesus never says very much or leaves what he says up to the interpretation of others. Try and convince her parents that they are wrong in their views and provide biblical evidence. Map out your argument beforehand.