I'm sorry but it is not unrealistic, people just want to think it is.
(btw, sex is beautiful when you share it with someone you love. It's only bad when you do with someone you don't care about or you regret it)
I think kids are going to hide it from their parents anyway.. it's a privacy thing. At least hide their first time from their parents.
I mean, would you like your mother come with you to your gyn doctor now that you are a grown woman? I don't teens would either. As sex will always be a private matter.
Sadly, people are able to pull this off with smoking and drugs, but can not tell kids to wait on sex.
