Although I have discussed this before, sex is used as a substitute for affection. Affection isn't manly, sex is manly - and men want to be men, rather than wussy and wussy is needing anything, especially affection - but we are mammals and we've been needing the warmth of fellow mammals touch for millions of years.
So many of our problems stem from sex. I was recently reading about the problems of being openly LGBT up until quite recently it has been laced with shame, persecution, often violence and stigma. Pedophilia, rape, abortion... and at their very root is the taboos on sex.
Sex is a minefield for teenagers because no one talks about it, adults are embarrassed, like it is something shameful, when sex really is something like eating or using the bathroom, we are designed to reproduce and reproduction is something that needs to be done rarely especially with the benefits of modern medicine and the prevalence of food. We now live longer lives and death related to birth, whether it is the mother or the child is not like it was even a hundred years ago.
Now I think only people who really want children should have them, given the number of children in the foster system. We should take care of the children in need of a home first before forcing people (women) into having children they don't want.
But teenagers who are starved for affection and faced with the taboo of sex - will often opt to experiment.
There are all kinds of reasons why people eat but mostly it's meant to be fuel. People have sex for all kinds of reasons too, and while orgasm can be enjoyable and can help relieve tension, a partner is not strictly necessary, not unless you are planning to reproduce which is a decision that has to be made carefully because it involves so much responsibility.
As someone I once knew said, men give love to have sex and women give sex to get love. And this causes all kinds of problems too.
What we really need is that everyone gives each other affection, instead of using sex as a substitute for affection. Affection relieves stress and tension too without the consequences of unwanted pregnancies or diseases. And I am sure this would help heal and prevent so much damage done in the name of sex.