Well, I wouldn't say I was happy he chose the other girl, but I am glad he didn't go with the main girl. Because, it really shows how first loves can sometimes NOT work out for everyone. Especially if you act the way she did. I'm glad she had her own learning experience and realized herself that what she was doing was wrong. And, if the boy had left the other girl to be with the main girl, that would have been even more wrong! So, I wouldn't say she is a sadist but she did what every other person would've done if someone they liked was liking someone else. It's more so her jealously taking over rather than just being a sadist. Everyone does stupid stuff when they really like someone. That's just my two cents.
This needs to happen to every girl and guy who tries the manipulative jealously ploy. Playing with peoples emotions like that is despicable. I'm glad he chose that other girl. She lost my sympathy when I saw she ENJOYED his sad face. Freaking sadist.