Usagi kept holding his hands because she felt like she'd fall as soon as she let go. Why did ice have to be so slippery? And hard and hurt a lot when she hit it when she fell? Okay, so it all came down to her clumsiness but she'd rather blame slippery ice than her innate ability to lose her balance so easily.
She managed not to fall yet. "Okay, I'm gonna let go," she told him once she felt confident enough to do so. So she let go of his hands and slowly glided a few feet. She did almost fell, flailing her arms in the air before the regained her balance. When she did, she grinned. "This isn't so bad."