You have to have met your fiance in person within 2 years prior to submitting the fiance visa petition. After that, presumably you would have also kept in touch and met in person if it is a valid relationship. If you did not, perhaps the USCIS determined that it was not a bona fide relationship and that is why it was denied. I have no way of knowing the exact reasons without knowing all the specifics. However, if you believe that the relationship is valid and the denial was in error, there is nothing preventing you from refilling another petition.
Answered on Oct 22nd, 2013 at 2:20 PM