The way she went from her usual tsundere-bashful to realizing the guy is actually a rare catch indeed... Haha, I love it!
I mean think about it: The guy went from literal ant to someone who could fight side by side with her in little over one and half a year! By almost (or actually) dying several times!! Just for her!!!
That's some seriously dedicated courtship!
No wonder she's swooning. The guy's an absolute madlad!
Another thing is, this and the previous chapter kind of confirm a theory I've had since very early in the first season (partly due to reading the prototype first).
I'm talking about how she would always seemingly hide behind Outer Moka and let her deal with any and all social interactions.
She was always afraid she would somehow muck up her relationship with her friends and especially Tsukune. Likewise, her pretending to be distant so in case things do indeed go wrong she wouldn't get (as) hurt.
That said, I don't think Tsukune was/is only important to her because she 'likes' him. Rather, it's thanks to his influence she was able to gain her circle of friends in the first place. And considering her experiences with people in the past, he likely also represents something like a new lease of life to her. Dude single-handedly changed her life.
Finally in this chapter she realizes that no, he won't run from her and he isn't weak enough to simply die on her either. That yes, he would indeed never abandon her.
Hence, her entrusting her back to him.
...I like it.