I don't think it is a keng. Even it is, I believe there are lots of people who has experienced tremendous pain during their first sex, and most often, it is not successful.
I suggest LZ to search the word vaginismus, and you may find lots of information regarding this.
These are two websites that you may find useful:
http://www.marriagebuilders.com/graphic/mbi5049a_qa.html
http://www.vaginismus.com/vaginismus-symptoms
Good luck.