When a man and woman are getting to know each other for the purpose of marriage, the man can see the woman without her hijab one time only, with the following conditions:
a) The relationship has reached a stage where marriage is intended and the man wants to see her before finalizing.
b) It is not done with the intention of seeking pleasure or doing anything wrong.
c) The man has not previously seen the girl without her hijab.
d) Only the hair, neck, hands and feet should be exposed. Exposure of other parts of the body is not allowed.
Modesty is a big part of Islamic teachings. All aspects of a close relationship between a man and woman who are non-mahram to each other must be within the boundaries of marriage. Marriage is highly recommended and many rulings facilitate and encourage marriage. This ruling is part of that outlook. It is not setting aside modesty, there are conditions still in place. No touching is allowed. A limited, conditional gaze exception is made when the intention of marriage is serious and requires this last step to finalize it.