Uneducatedly.

Or they will become adults, start relationships and lose touch.

I agree, and i'm probably younger than Xas but i've had a few bad experiences where i've been very close to female friends and well, they just dont work. What's even worse is when you're close to a couple of girls, both who know each other, and one of those friendships turn into a relationship. That is just ugly as hell.

Yeah, they may as well go their separate ways now and enjoy the fond memories, rather than dragging this fruitless "friendship" thing on to its inevitable conclusion of mutual contempt.

That'll never happen though, everyone always has to learn the hard way because everyone thinks they're different to everyone else, "we wont end up like that, we're different to you, just because it didn't work out for you doesn't mean it wont work for us, etc etc"

Yes, you're right. I've long forgotten the arrogance of youth.

This is all some very bad advice. Men and women can be freinds, and there is no reason to keep it platonic. If she has a sister, there is no reason to keep it platonic with her either. If you insist upon foregoing the enjoyment of each other's intimate company in the future, especially since you have enjoyed each other's company in the past, then, well, I can't help you.

There will not be any resentment until one of you ends the sexual relationship. For whatever reason, doesn't really matter. Maybe one of you meets that special someone and decides that monogamy is better (do not try this until you are at least 28 or 29 years old. Trust me.). Maybe Xas will convert and join a monastery. Whatever it is, something will happen, and you will just find that the freindship fades away, you will go on with your respective lives. Then, one day 15 or so years later, one of you will remember the special times of your indiscretionate youth. Maybe Kara will see Xas on ESPN2. Whatever it is, you will try to contact each other again, maybe even meet up, and have a truly awkward conversation where you realize that you have nothing in common any longer.

But by then you will have a much better understanding of the world and your place in it. But do not give up sex with each other in the mean time. That is just crazy.

Just my $.02.