Uhhh . . . I don't know how you got "Hey, go **** everyone you want without a rubber" from what I said, but that's not my message. 17 isn't really a good age for ANY of that stuff. I know the occasional tryst or relationship WILL happen, I'm only saying that taking them extremely seriously at this point is ultimately worthless. I believe there's an area between the ages of about 18 and 25 where MANY changes occur within a person, if for no other reason there are many situational changes. Within those ages, a person will most likely: move out from under the protective watch of their parents for the first time, make their own decisions, live on their own, be responsible for their own management of time and resources, pay bills, and so on.
She will not be the same person in her mid-twenties that she is now. Any relationships forged right now will, along with her, undergo the same metamorphosis, and it's one that many relationships seldom survive. I leapt into a serious relationship with someone when I was 19 years old. Five years later, I have the divorce papers to prove what a mistake that was.
Be young, have fun, don't be quick to tie yourself to one person and hope it'll be forever. Odds are excellent it won't.