tori moller [jessica pare] is a young woman in lost and delirious who is in love with another young woman, pauline "paulie" oster [piper perabo]. they have an intense--but secret--love affair that is abruptly put to a stop when tori's sister [emily vancamp] and her friends catch her and paulie in a compromising position.
tori, afraid of being ostracized and cut off from her family, betrays paulie by denying their relationship to alison. she tells alison that paulie just crawled into her bed and that she didn't know she was there in an attempt to clear her name, repeatedly stating she's "not like that" [not gay].
she further stops communicating with paulie and quickly gets a boyfriend to prove that she's "not like that," occasionally elaborating on her sexual escapes to her friends. this drives paulie to desperate attempts to win tori back.
most people would hate tori for betraying her paulie, but through the eyes mary "mouse" bradford [mischa barton], you see tori suffered just as much as paulie did, hiding herself and denying her love to paulie--pretending to be someone else.