"If sex were dating, Santana and I would be dating."
If sex were dating there would be roses, from Santana to Brittany, and soft, cuddly toy ducks with ribbons around their necks. There would be dates at Breadstix without Finn, or Puck or the pretence of friendship. There would be kisses after practice and before class, by the lockers and during Glee, where there would also be ballads, because really, at heart, Santana's a romantic, and there would be displays of affection that would send Puck running for the bathroom. But sex isn't dating, so there are none of these things.
"Just do what I do. Never say no."
If sex was more than just sex they would be exclusive. It would be Brittany's kisses alone that leave purple flushes at Santana's throat, and only the Latina's fingertips that have her team mate trembling at ungodly hours of the night. There would be a level of intimacy that surpasses any relationship before them, outstrips any connection they felt with any other human being, because there would be a depth to their relationship that was lacking in all others. There would be things that only they knew, like Brittany's habit of grabbing her lover's hand during climax, or the extremely sensitive band of flesh that follows the curve between Santana's hip bone and her stomach. They still know these things of course, but sex is just sex, and so the knowledge is meaningless.
But sex will never be just sex, at least not where Brittany is concerned, but it will never, ever be dating either. Because Santana has spent the past two years teaching Brittany that every signal she's ever sent her means nothing, that sex is not dating, that she doesn't need her, that how they feel is not okay. So Santana will forever be alone in love, because even when she tells her, she tells her too late. Brittany takes her cues for Santana, and Santana never taught Brittany that she needed her to love her back.
"Please say you love me back. Please?"
And Brittany, for all she knows to be true about Santana, will never know this.