That's a good point about her being frightened. At 15, I had just met my future husband (we had a class together), and my entire store of "knowledge" of sex and romance came from Harlequin paperbacks (I mean, I knew that Tab A fit in Slot B, but apart from that, not much else). So in all likelihood, were I Sara, I probably would have reacted in much the same way -- deer in headlights. My 33-year old self wouldn't have, though :). (Of course, I think DB was all of 35 in that movie, so.) I guess what was sort of dissonant to me though is that she became so very strong throughout the movie, and so decisive, and then at the end she reacted the way she did, but maybe that's the point, that while she grew up and made huge strides towards adulthood during the course of the move, she wasn't there yet.

I suspect that is why there is so much fanfiction with Sara and Jareth after she has grown up a bit. She was too young for him, but she was strongly attracted to him too, I think (is it possible not to be strongly attracted to Jareth?!). She just didn't know what to do with it other than to not deal with it at all.