[Because she is watching him so intently, expecting to see all of those emotions she indeed finds in his eyes, he can't hide the conflicting feelings like he usually would, can't brush what happened aside and pretend it was just a simple joke. She is not buying it.
And she looks crestfallen, the bliss she had only started to experience a few seconds ago vanished, leaving her cold despite Hak's arms still enveloping her.
Maybe normally she would have pulled away, but here she can't bear to be anything less than honest and there is a hint of anger, mixed with a childish stubbornness showing up on her face. Instead of turning away she stares him down, not accepting defeat when she is so sure that this is what she wanted all along. Yona wants to be even closer to him, as close as can be, and she can't do that when he is so obviously pushing her away by denying what he really feels for her.]
No.
[There is force behind that small word, determination not to let him get away.]
I know you aren't just teasing me. I am not accepting this.
[And because actions convey a lot more than simple words, she practically climbs on top of him, pinning his arms to the bed as she puts her weight on his pelvis. Yona fully realizes that she is no match for him, that if he really tried he could just brush her off like some annoying fly.
But it's not all she does. Instead she also bends down and kisses him before he can protest too much or try to disentangle himself from her. Though her inexperience still shows, this kiss is very different from the last, driven by a need. For him to stay with her, forever if she has any say. For him to return her feelings, to kiss her back, to just hold her and never let go again.
She doesn't say the three words - it's all still too fresh and embarrassing for that - but hopes that he will understand regardless and that there'll be time for that later.]