Her hair is yellow and fits just right in his hands in a way that Hermione's never would. It is all shiny and straight and golden, and isn't that just wonderful? It is perfect to pet and stroke and mess up and tangle one's hands into. It is the color of sunshine and daisies and butter…and isn't that how that spell that didn't work began? That spell he tried in front of Hermione when he first met her?
Yes, Lavender's hair is by far better than Hermione's. It's is a field of flowers, or at least it smells like that. Whatever she washes her hair with smells of flowers. Perhaps it smells of lavender…perhaps her name is her signature scent…but he doesn't quite know what lavender smells like, so he can't be sure.
She is pulling away from him to giggle, but his hands are still trapped in her hair, a big ray of sunshine, just like her smile, but he doesn't really feel that way about her, or at least he can't make himself. And as she leans back in for another kiss, he thinks he sees a flash of untamable, loving, loyal brown amid the rush of sunshine and flowers, running by, just as mass of hair really, since it's hanging in the face it belongs to…but as he comes back up for air, he realizes that this cannot be so.