Soon as you meet a new girl you'll forget about her.

Guys often have crush on certain girls for the strangest reasons. For instance, "she smiled at me", "She started talking to me when I never talked to her", "We did dancing class together"

If you think that fantasizing this WoW girl is strange and want to stop then get out in the real world and waltz into some random shop. You might find a girl who your strangely attracted to.

If you are confident that your making a right choice by fantasizing/eventually asking out this girl then by all means go for it.