Pretty much what's been said. Fanboy intensifies the idea that someone has an irrational hatred/liking towards something. Fangirl doesn't convey that.
Besides, it's not like it matters. Political correctness is annoying sometimes.
Kimi wa ne tashika ni ano toki watashi no soba ni ita
Itsudatte itsudatte itsudatte
Sugu yoko de waratteita
Nakushitemo torimodosu kimi wo
I will never leave you