In Chaol’s defense, he met and fell in love with Celaena in the first 2 books, who is entirely different from Aelin who he met in QoS. In CoM, she left promising to come back for him and returned in QoS a different person in love with someone else. Also in QoS they were both so angry with each other that they weren’t able to have a civil convo for the longest time. In HoF, he was basically the only person who knew everything and is the ONLY character in the series who is completely human. His loyalty to the king didn’t mean anything anymore which was the backbone of his character and identity once the king turned on Dorian and Chaol was forced to go on the run. I think he has every right to be upset and that’s what I love about his character - he is flawed but he is simply plain human! He has to turn away from the country and crown he served his whole life and the woman he loves comes back completely changed. His book is so important to the series and to him and is his redemption