Marrying cousins is very common among Muslims.  I heard it is very common among Magars (According to one of my Ghale Magar friends).  Not only these people can marry their cousins, they have to give first preference to their cousin for marriage.   That means, as long as there are marriageable cousins available, they are not allowed to marry anyone else.  If they marry with anyone other than with their marriage aged cousin, they must get consent from her/him. 

But our society does not accept this kind of marriage.  Just do not do it!  Even Muslims or Magars are realizing there is something wrong with the tradition they believe in.  Even they are avoiding marrying their cousins these days.  I read a similar case few years ago. Cousins in India fell in love.   After giving long thought on this issue, its consequences - biological as well as social, the girl decided to split!  She was a doctor and moved to Canada!  She kept on calling/writing to the man once in a while and slowing moved away from her cousin's life!  She married another man and that was the end of the story.

Splitting will be difficult, but can be done.  A couple in love recently split when an astrologer told them about "Mrityu Yog" if they marry. One of them was going to die after getting married - that is what one astrologer told them.  I believed they reconfirmed with another astrologer.  All the love between them vanished and they mutually decided to split!  Sound funny to some people, these love birds split because of one astrologer! 

Spitting is painful, so is divorce or death of a spouse.