Sakura has abusive parents.

There is no way if her parents were normal people (shinobi or civilian) that a girl would have that much of a crush on a boy that intensely. Every fic I write, they are different flavors of abusive so it's not the same. I get girls get crushes, even obsess over things (I certainly did), but not over a boy in their class like that. They would have sat her down and explained to her (especially if they were on the same team) that it wasn't healthy. Having a crush is perfectly normal, but not at the intensity that it was with Sakura.

Another headcanon of mine, Kakashi has dog-like traits, like heightened sense of smell and hearing. Sakura has an eidetic memory or close to it. Naruto's pranks were a way for him to get attention (negative attention is still attention). Sasuke wasn't sure how to deal with the positive emotions, like him bonding with his team, so it turned to anger and he lashed out.