Is it ok for a 14 year old boy to fantasize about a 8 year old girl?

Yes,you are free to fantasize over somebody of that age (of course if you are 14) however any action taken on the subject may result in Un-happiness and arguing.

These situations are very hard to deal with but im 15 and i know alot about realtionships:) Take my advice,keep your relationship with him/her nice

Dont go and chuck any relationship away you have,You might need it one day!