He is not going to be deported but it may be that his student visa is not renewed and he is not permitted to continue taking classes until he leaves the country and reapplies for a new student visa.  A violation of one's international student visa status is taken very seriously.  If you want to get married, you can do that and then file for his adjustment of status on the basis of marriage.  In that case, he will no longer need the student visa.