She was clearly still mostly asleep, probably in pain, on potions, she didn't know what she was saying. Maybe she didn't realize who it was? In the dark, from the back, he could be anyone. He didn't turn, he couldn't stand to see a welcome in her eyes, and he didn't want her to see him cry.
"I didn't mean to wake you up," he said quietly, voice almost monotone. She would recognise him for sure now. "I just needed to," make sure you were alright. "But I'm going now, don't worry."