The first time Buffy had sex, it was with Angel.
Angel smelled like all vampires do. Underneath everything they can do to change their scent- lotions, perfumes, powders- he was dead flesh, grave dirt, fine bone dust, and blood. Sex added a muskier scent to him, and made the other scents stronger. In her mind, that was linked to the smell of sex. That made sleeping with Riley much more difficult, because Riley didn't smell dead.
Sometimes she could close her eyes and pretend but he never smelled right.
And then Buffy died, and came back, and Spike smelled right. Smelled better than right, with his aroma of cigarette smoke, hard, cheap alcohol, and blood-and-dust vampire scent. It was ok for a while, sleeping with him every chance she got. It meant she could pretend that the dead scent on her skin was his fault.
Not hers. Not a part of her now, unclean, absorbed into her cells when she clawed her way out of her coffin.
But eventually she had to say no, refuse him. Start standing on her own two feet again, and accept it. So she tried.
Then Tara was killed, and Willow blossomed darkly.
Willow had always smelled of safety, and innocence, and home. With Oz, there was a scent of the wild about her, and as she grew in power, a mystic scent, like the one that covered Giles, like the one mixed in with her own, became clearer to Buffy's nose. With Tara, Willow smelled more of honey, sweet female scent, and the magic they used together.
Then Willow was there, black hair and changed face, and the magic in her scent was under laid by blood, Tara's blood, and something darker. Something deeper than anything Buffy had ever smelled.
Since she's been back from England, Buffy has been waiting. Smelling how Willow has changed, how she has the scent of growing things, magical earth, tea, and death on her. Not death the way Buffy and Spike and Angel have died, but the death like theirs, where they have killed.
Killed, and enjoyed it.
It's almost distracting, noticing how good Willow smells. But Buffy can't afford to linger on it, and besides, what could she say? "Hey Will, I know I've never said anything, but there was this thing with Faith, and I know you and Tara, like, and right now you smell so good, and we might die soon, so, you wanna?"
No, that wouldn't work. She loves Willow too much, needs her friend more than she needs a lover. Needs that magic on her side, but not distracted. And the scent of Willow gives her hope, because even with death all over her, Willow is still beautiful. Still desirable.
Maybe Buffy is, too. And maybe, if by some miracle they survive this, survive the First, the end of the world and everything, maybe then she can say something.
Maybe not. After all, if they survive, there's going to be a lot more people smelling like death. And Willow has always been the best of friends. Why ruin that?
There will be other girls with sex and magic and death scents, but there will only be one Willow. And Buffy wouldn't change that anymore than she'd change Willow's scent.