I just watched The Crush with Alicia Silverstone (from Clueless) and Cary Elwes (Westley from Princess Bride). Was quite good. Wasn't supposed to be (same way zombie movies aren't).
She's 14, he's 28. He rents a place in back of her parents' house. She gets a crush on him. He waffles a while, then refuses her advances because she is young. She gets upset, goes a bit crazy, ends up assaulting people, accusing him of rape, and finally is put in a mental institute (where she gets a crush on her doctor to end the movie...)
She was nuts; he was normal. He didn't do anything wrong, and once the truth came out, he was vindicated, and she was condemned. And that's that. Right?
Except, if you watch closely, it's not like that. When the girl fails, it's not graceful, and she hasn't got mechanisms to cut her losses. She should have given up on her relationship with the guy, instead of taking more extreme measures. She should have been more reluctant to involve and hurt other people (collateral damage). Those are certainly very major flaws. But they are not nearly the whole story.
The guy starts the badness and cruelness, and is very very ageist. Other people treat the girl badly, too.
Very early, she asks him what he's doing. He indicates she wouldn't understand. She insists he try, and she understands fine. He is a journalist, who's very good at researching cases, and less good at doing writeups. She edits one of his pieces, and significantly improves it. At this point he should recognise she's intelligent and stop treating her with kid gloves (he never should have made that assumption, but now it ought to be dispelled for sure). But instead he's angry! And indicates he doesn't like being shown up by a 14 year old.
It goes on. He's clearly attracted to her, but he tries to deny it. How this must frustrate her! Eventually, he tries to explain himself. He says that she is 14 and he is 28. That is his entire argument. He doesn't even know how to elaborate on why that should matter. He is nothing less than horrid.
Reasonably, he had legal fears, but never once did he mention this (even should they get along for say a year or two, breakups are kinda normal, and if she was upset then, it could be quite bad for him legally).
Reasonably, he could be worried she did not fully understand what she was getting into. But if that was his objection, he shouldn't just mention their age difference and insist they could not have a relationship. Rather, he should simply insist on a gradual progression. There are all sorts of perfectly benign, safe things they could have done together until they worked out some convergence on this issue. Examples include talking about his work, discussing writing technique, playing frisbee, researching wasps, and watching Dawson's Creek.
Reasonably, he could be worried that the relationship would be unbalanced, and that he would not like that. Because he's too busy, too scared of commitments, or just didn't like her enough. But as far as I can tell, this wasn't at all the case, and he did want her, and he did have time for her, etc
So why was he saying no? Because he was ageist. That's it. In this light, it's fairly understandable that she did not accept this answer and drop the issue. She knew she was being jerked around for no good reason, so she insisted more strongly.
Imagine you were white and asked out a black girl, and she said she didn't date white people. Alright, the best thing to do is drop it, but being a bit upset would be understandable. And if you really thought you were Meant To Be with her, you might think the only problem here is racism, and that is not your fault, so you shouldn't be rejected over it. Rather, perhaps you should get to help her fix it.
Once he decides he does not want the relationship, and puts his foot down, he is not kind to her again, all movie. Not even when being kind to her would have obviously, directly, made his own life better (he should be kind much more often than that, basically whenever they do interact and he doesn't have a compelling reason not to be, but the way he hurts himself to be cruel is very revealing). Instead he scorns her, and treats her as if she is not rational. Yes, she goes beyond the bounds of civility, but he'd already gone beyond the bounds of morality. (This isn't meant to defend some of her later, more extreme actions, but rather smaller things like stealing his photo.)
Also of note is that she is extremely competent. She steals a used condom to make her rape accusation more compelling, and puts on a good act. She escapes her parents to return to her house when they try to hide her away at a summer home. At one point she has a horse competition, and he doesn't come, which upsets her. She doesn't mope around. Rather, after it's over, she immediately finds out where he is (a business event thing) and takes a taxi to it. Walking in, she finds him and sweetly says "Hi honey" and kisses him on the cheek! Angry yelling would have gone very badly for her, but this was perfect. He was terribly embarrassed by her age, and the scene, and came off very badly to the audience (he tried to get rid of her, she tried to kiss him, he got physically forceful, she screamed a lot. He should not do that). When he tries to move, she tells his potential landlord he deals drugs. Quite effective.
In summary, she was messed up, but he was too, and I think our society is blind to his errors. Our society doesn't understand age gap relationships (or romantic ones).