The best term for it is probably 'body-shock'. She's watched Rob go about his life for long enough that she can fake the social interactions--at least enough not to draw too many questions--but all the demands and limitations of a physical form are distracting, to say the least. Her mother had always scolded her to mind her details, and so she had, and now she can barely think past the watering of her mouth when she strolls past a bakery with Rob and all the smells come rolling out upon her like a tide.
They're both mortal now, and she can feel life already slipping away from her, like water through fingers, the scouring away of mountains, and yet this body demands sleep, ungraciously charges her time for time spent. She refuses payment for two days and then the body collects its due with interest and sand scrubbed against her eyes.
Rob laughs at her, but gently, wonderingly, makes her take his bed and promises to still be there in the morning.
And he is, and they have pancakes with butter and syrup, and none of the delicacies of Atlantis at the height of her luxury could compare to the sweetness when he kisses her after.