It has taken Hermione a stupidly long time to realise that Malfoy is just as afraid as she is. Not just because of the physical aspects, and the awful associations that certain acts have for them, but because he's afraid of the emotional consequences. She thinks that for Malfoy, sex would be like admitting their feelings out loud, and he's not willing to do that, to open himself to that hurt and that vulnerability. Which is enormously stupid of Malfoy, because refusing to acknowledge and act on his feelings doesn't protect him from suffering that hurt and vulnerability anyway. Idiot.