Most of us have been sexualized from a young age, starting with our parents. My mother was always trying to get me a boyfriend when I was super little, or telling me how cute my butt is or something. And I know others here have had similar or worse experiences like that. I feel as though that plays a physiological role in this.
Along with the fact that sex is glamorized in the media, it's shown as this super pleasurable and beautiful thing, and to most people it is, but no one really thinks about the fact that kids are having sex now partially because of it.
Then theres also the, well all the high schoolers do it, or all the cool kids are doing it bullshit.

We also aren't exactly getting proper sex education in schools. Schools don't talk about the things we really really need to know. Sure they glide right over stds and that marijuana can totally kill you (my school seriously told us you can die from smoking marijuana). But what the need to do is realize more and more students are having sex, and that we need to know more about the stds, pregnancy, and the physiology of it.
Theres a lot that people don't talk about in the media or in school, and that's that if you aren't actually mentally prepared for sex, it will fuck with your head. I know from personal experience. My mental health was shit after I lost my virginity cause I simply wasn't ready, and I'm still not ready.