Link wasn't sure why he was helping Groose, packing him a bag so he'd have worldly possessions down on the surface. Maybe his heart broke when Zelda sealed herself away, and it had made him softer than usual. He's not sure why he's helping Groose, but he knows why he's doing the same for Zelda. Decorating around the crystal she's sealed in, wrapping a blanket around it so she's nice and warm, reading to her just in case she can hear him. He would do anything for her. Hylia counted on it, and she was right. After all, she's still his Zelda.