I must assume that your young, say around 18 or maybe less. Most asexual people make great friends, but have a hard time in long term committed monogamous relationships.
The first question that you must ask your self, IMHO would be why is this person asexual?
I think that will shed a great deal of light on your choice. Being sexual is a major part of a health partnership, no matter what your sexual preference might be.
Best of luck with whatever you do,
Calosis