It's incomprehensible to me how Noa gives them this reaction.
I know the internet lends itself to extreme opinions, but the reason Noa elicits so many horny thoughts isn't
just because she's obviously physically attractive.
She genuinely loves Rihito. That love wasn't romantic for the first 40 or so chapters, and you can argue it still isn't, but there's a deep care and appreciation running deep between them. Despite of what some loud voices say, romantic love on a level like what we've been shown elicits strong sexual desires. Noa could be a stick woman with concave chest and tube legs, and she would still have hordes of people wanting to fuck her because the idea of having someone caring for you and loving you in the way Noa does for Rihito is extremely attractive. Even if she's a bit too much, objectively speaking.
Now, at this point, Noa could still pivot towards purely platonic love for him. (But, come on, we all know what genre we're reading), but that wouldn't change the emotional attachment people have towards her and Rihito's relationship.
But that's just my two cents.