there is nothing illegal as long as you don't have any sexual contact with the minor. i know Clinton made fellatio a very popular thing but that's part of the deal too.
Instead of worrying about the ramifications in the event you two do get intimate wouldn't it be a good idea to find someone who's a few years older? I'm one to talk dating someone who was 8 years younger than I, however, we were both over the age of consent.
May I suggest being friends? Take her out to movies, dinner, etc. but seriously, don't get your hopes up for a long-term relationship.