Panic.
That was all Valerie could feel as he struggled to save Islinda's life. He did not expect to see her on his doorstep, not like this. Something must have happened - something that made her trek all the way to the cottage without any form of protection against the cold.
Valerie was enraged at her. But the need to save her life was far greater than the anger directed at her. Human lives were fragile and short-lived. While Valerie was aware of that, he did not think about it while spending time with her. He fooled himself into thinking that they had much time together when she could easily be eliminated from this world.
It didn't help matters that she had fallen unconscious. He had no idea how to cure humans. This was winter and he was a summer Fae. Fire and ice are natural enemies and some of the lower Fae are susceptible to frostbite.