Yuno wakes up tucked in on her bed at the Palace, she can barely get up.
Kai sits beside her worried, he got better but she's still pale looking, "Yu said I can stay here for three days, I'll go see cousin Rie when it's her turn, how are you feeling?"
Yuno closes her eyes, "I need sleep, don't worry about me."
"I'm trying not to, but I can't." Kai feels for a pulse and sighs in relief, Yuno must've absorbed all his pain somehow or something, or maybe this is the side effect since her body was healing.
He's assuming the exhaustion resulted from her ability over working itself, he's not surprised Yuno's ability is constantly getting stronger, especially since she came to the Palace, she has been secretly healing people from day one.
She doesn't even bother asking what happened she just heals them, and eventually she told Sensen about her ability but asked her not to tell Ken and obviously the old hag kept her mouth shut.