Sally thinks sex is normal. Sally thinks Bob is cute.

I think it relevant to add that Bob also thinks Sally is cute. The word cute has sexual quite clear sexual connotations.

like any healthy teenage boy, fairly horny

Considering the context and common sense analysed through they eyes of someone a bit neurodiverse, this sentence dosen't imply that he wants sex more than Sally does. It just implies he wants sex with Sally more than she does with him.

But this dosen't mean Sally dosen't want sex with him, thought this is what I first read into it (see my other post).

For the desires to be paired Bob would have to be much higher status than Sally due to the differences in hypergamy between the genders.