Bellatrix had been distancing herself from the Dark Lord as she had been busy trying to track down the last horcrux's that had gone missing but hadn't been taken into the Orders protection to later be destroyed. She was spending more time reading, drinking, smoking, torturing various hostages. She had been somewhat making normal conversation with Hermione again, but after their argument she knew that the younger witch had developed some form of feelings, and she wasn't ready to accept or deal with it. When she wasn't busy doing any of these things she was busy sleeping and waking up at ridiculous times of night.