When you talk about “prime reproductive years,” know that it includes girls as young as 10.
Prime reproductive years for women is generally late teens to late 20s. I'll keep using the term because I'm using it accurately, and it's exactly the whole point: biologically speaking why would it be surprising that some men would find a women who is prime for reproduction attractive? It just makes perfect sense.
it’s confusing when confronted with a genuinely attractive woman that is not yet 18,
It's only confusing to you because you've bought into the puritanical notion that there is something wrong with being attracted to young women; there's really nothing confusing about it: it's reasonable to find them physically attractive, but almost certainly inappropriate to engage in a relationship with them. This is the misconception I'm trying to dispell here.
I agree that at best he did a questionable thing. However I know nothing of her maturity at the time. As I've said elsewhere, I've met emotionally and intellectually immature 40 year olds (certainly plenty in their late 20s) and intellectually stimulating and mature 16 year olds. If it's legal, and she was mature, why would it be wrong? And would it be wrong if I had sex with "a fully formed adult" when she is emotionally immature? I get we need a rule to catch the vast majority of the cases, but from a moral stand point I can't say why it would be okay to have sex with an emotional immature adult, but not okay to have sex with an emotionally mature adult just because the latter is younger than the former.
Again, don't get me wrong, the vast majority of the time there is some taking advantage going on, and there should be laws to stop it. I'm not arguing against this.