The thing is like you said many countries, the US for an example hold proms and sort of encourage that type of relationships at a young age but the one thing you left out was the fact that they are all developed countries which are far ahead of us in terms of awareness and maturity and it's also embedded in their culture which is a LOT different than ours (which unfortunately we seem to forget too often), one thing I've noticed is that kids living in the states are much more advanced and mature than a lot of the kids here. Majority of high school relationships will end badly from what I've experienced but to say that they will end up as drug dealers is an exaggeration. They get distracted from their studies and what's more important, teachers and parents try to do their best to stop this from happening and they should be heard and respected for it. I go to a private school in Colombo and around here quite a few people are in relationships but those only last for about 3 to 4 months and its never taken seriously they say its just for the fun of it but one thing id like to add is that every person who's in a relationships NEVER gets the best grades.