There's something to be said about the way Yangchen immediately notices that Kavik is good-looking and tells him to his face right away. I think it's because she's not used to feeling attraction and therefore she's stating it as a fact, even when Kavik's teeth, cheekbones and most importantly lips keep living in her head rent free. She values and appreciates their bond (before the betrayal), tells him as much, but it's admitting internally to herself that she does in fact find him hot where things get stuck.
Kavik on the other hand yaps internally and to other people how pretty she is but would probably die of embarrassment if he were to tell her directly, and as the book progresses, his internal commentary about her gets more and more sappy, it shows more and more how deeply he cares about her and wants to be beside her. He doesn't exactly have a problem recognizing that he's attracted to her, it's the deeper feelings that are troublesome.