You're still young Atnas. You have plenty of heartache to look forward to. Your situation is only the tip of a brutal, brutal iceburg. Just wait till things start getting physical, you move into the same house, occasionally sneak around behind the backs of your other housemates (because nobody's supposed to hook up with each other - those are the "rules"), then she suddenly decides to go out and start picking up townies at the bar, either bringing them home or just not coming home for days on end, leaving you a shattered mess, and you end up sleeping with another chick you've been friends with since you were 2.
bet she's just seeing who likes her more, my suggestion would be play like she does, just keep the relation you have now and make her fall in love with you, because if you throw your feelings at her she might pull a kane and lynch and like make you gtf away.