Hermione recalled that after they had burned through their passion last night they had talked a little and agreed that this was something that couldn't happen again. It didn’t make sense for them, she wanted to focus on her education and career and finally get to be herself for once, not part of the "Golden Trio’, just Hermione Granger. It didn’t make it any less upsetting that she knew this was the truth. Malfoy had agreed too so she knew it was mutual.