Religion on one side, in my opinion it is more the culture that you have to be aware of. This does not mean you wear skirts covering your ankles and your Prince's baggy shirt.
If you are visiting Kurdistan with him for the first time, to be introduced to La Familia (or is it Le? However, skirts should not be above the knees, don't show too much cleavage, t-shirts are fine, these are all guidelines to start off with.
Not because your in-laws are evil devils (in fact they might be just a little bit too nice) but keep in mind that while your Prince has lived in the west, your in-laws haven't. * Usually, saying "I do" the islamic way -- which is how the majority of Kurdish girls get married -- includes sitting in front of the Mullah (religious man) and saying yes to him. ~Don't be under an impression she is an evil witch, because she has the sweetest words and is filled with lovely emotions. So it is only natural for them to observe you very closely and criticize some of your decisions/ actions at the start. No, to be honest i think they enjoy young, free, beautiful girls. Most recently, I got an email from someone who has already said yes.