Leia has been Hux's hero since he was tiny- the brave tactician and politician who was leading an army before she was 20. He even had the occasional seditious daydream that the Rebel Alliance would attack Arkanis, and she'd recognize his obvious talent and take him under her wing (and maybe adopts him and they rule the galaxy as mother and son).

+ finding out that Kylo 'the worst' Ren is her son, and threw away the life that Hux dreamed of
+ meeting with General Organa over negotiations and trying to stay chill
+ 1000 go for broke- the only reason that would make him even consider defecting would be Leia trying to recruit him. She does.

Prefer if it were non-sexual admiration.