To me, the original beginning sounded a bit like backstory. There was no action in it; it wasn't a _scene_, just some narration. Now the bit you suggested is exactly that -- a scene, full of action and conflict. Although I'm really not into teenage sex stories -- so I don't think I'd ever read this or similar type of book,-- I have to agree that the second opening you suggest is much much stronger.
To me, the original beginning sounded a bit like backstory. There was no action in it; it wasn't a _scene_, just some narration. Now the bit you suggested is exactly that -- a scene, full of action and conflict. Although I'm really not into teenage sex stories -- so I don't think I'd ever read this or similar type of book,-- I have to agree that the second opening you suggest is much much stronger.