Elsa's having the same problem. Her apartment – is it a home yet? Is it a home still? – is so... vacant. Of life, and warmth, and sentimentality. It's so still. There's no sound of scuffling and stumbling from Anna walking in, dead on her feet after a late shift. None of her snoring, or laughter.
No smell of cinnamon and honey hot chocolate to wake up to.
And it's strange, sleeping in her own bed. Nice, because it's so much more comfortable than Anna's lumpy mattress.
Just... she never realised how cold it was before.