To be fair, I don't think a lot of guys even register is until they're older.

The problem is you can't go advancing on someone when they can't walk away, but if you're only at work and school there is no other places for you to meet people. So if you come from a (archaic) background that thinks all that relationship stuff should happen naturally, you can't go out partying, get a tinder account, etc etc

You'd literally have to acknowledge that you want a relationship and all the things that go with it (namely sex), and while that's fine for a lot of people it's very difficult for others. Those others being most of the US by the way, religious or not those were the type of people who settled the nation, and that sex is a sin culture is ingrained in everything -- even if you're not religious or political.

This has even leaked into our medical views on sex because a promiscuous partner can very easily put you at risk for STDs. As such you certainly don't want to go out looking for relationships or sex because those are the sort of people you're going to come across, and that's a very real danger to your person.

You're basically left with turning off the instinct all together, which is unrealistic in most cases, so we end up with people claiming they're not interested in sex while being desperate for attention from anyone of the opposite sex. You probably knew a few people like that in highschool or might still know a few on tumblr. Anyone who does manage to at least deny the instinct is pretty much resigned to living alone for the rest of their life because they have of course come to this realization and decided not to change their views on the subject for whatever reason (likely fear of one of the many real or fictitious risks accompanying such a change).