in Rin's route. And here's why. (slight spoilers? but its okay the route is bad don't do it)
1. He's not endearing. He basically hangs around the art club because Rin is there, has no talent, and doesn't even make any other friends. He accomplishes nothing, except maybe encourage Rin to try to go for an exhibit. Contrast this to the other routes, where he helps Emi reconciliate with her dad (and has a plan for university), or Shizune get closer to her brother, by teaching him sign language. So he becomes generic, even to himself, and the route never resolves this problem.
2. He yells at Rin. Because she's bad at communicating. Which she tells him about earlier. So not only does he not "get" a large portion of Rin's character, he gets angry at her for it. Not only is this grade A jerk material, he also does it to Rin, who's probably the most stable of all the characters. He has the least reason to be angry with her, but also ends up doing it, to one of the more vulnerable girls in the game (Hanako being arguably slightly more vulnerable).
If at any point, he decided to get advice for his romantic troubles from someone in the game, they would've set him straight. But he doesn't, because to get the route to become contentious, he would've had to dismiss that advice. Because he's a jerk.
3. He never gets punished, for being a jerk, or making bad decisions. It's okay if people are jerks sometimes. As long as they realize they were wrong and there's penance. Hisao doesn't end up with any of that. He suffers no consequences for his actions, and as a result never seems to learn from his mistakes. He might've gotten better at understanding Rin, but he didn't become a better person. And since he was a jerk before, this means he get's away with being a jerk. Which doesn't help his case at all.
With all things considered, I feel sorry for Rin. Isolated from society, and the only person that's able to get close to her is Hisao, who is a jerk. The bad end almost seems better, if only that Rin might have a better chance at finding happiness in college, because it's pretty clear that Hisao's not able to be happy for her, or try to chase after her. He comes off as selfish, or self-centered, and never really lucid (in either ending) on what has transpired.
Still, the game's released, and there's no fixing the route. Rihoko friend-zone was pretty bad, but at least she has hope. For Rin, all I can see is tragedy. Fuck you, Hisao Nakai.
Edit: added tags
