Iran has more freedom than you think. Yes, the law about how to dress is very restricted there. But as far as I know for marriage law, Iran (Shia islam) surprisingly very flexible on that compared to other Islam sects. There’s no problem on marriage in Iran to married a non-muslim partner, even without any requirement (of course an agreement from both side men and woman is needed, even parents agreement are not needed for some Shia sects and its legal). But for sure exclusively, any muslim woman in Iran who’s not obey on how to dress properly according to Shia Islam (even she’s married with non-muslim), the punishment will severe.