My friend has this weird obsession...?

Ok so I have this friend and were in 9th grade and were all fifteen or almost fifteen...and my friend is obsessed with Yugioh and it's abridged series. Not the card game really...just characters like Bakura..and i'm not much of an anime person (i only watch naruto and death note sometimes..) and all of my friends are mostly goth and scene emo punk kids...she isnt really but she used to be and what happened was she was always a bit odd and she became obsessed with me earlier this year and she went bisexual and started saying she loved me like in love...and i am a heterosexual female so therefore wasnt interested in a relationship with my best friend...and she and i stopped being friends (for her benifit) and now were friends again but ive notcied over the month weve been friends that she has a weird obsession with this yugioh stuff...idk what to do or how to help her because it's unhealthy and she practically lives yugioh and it's all she ever talks about..she doesnt do anyhting but sit on her laptop all day on youtube and google...I dunno what to do about her...