There is nothing in Islam to suggest that it is not allowed to get married during the month of Ramadan because it is Ramadan, or in any other month. Rather marriage is permitted on any day of the year. If there is the fear that one may not be able to control his sexual desire, he should delay his marriage until just after Ramadan.

It is permissible for a woman to marry a man who is known to be impotent because intercourse is her right but she may waive it. If she does that, then she cannot demand this right after marriage.