@Tamerlane
As readers we know that Yang Guang is a crazy bastard that killed his wife and is involved in a bunch of shady businesses, but the teacher doesn't know about any of that.
To me, he's just as much of a psycho as Yang Guang, because his only motive for killing him was basically jealousy.
I also feel like he's too controlling. When Ye Limei started going out more, he was like: No! You should be making sculptures! Go make more sculptures!
He was basically telling her to keep having no social life.
He even used her phone without her consent at some point to message Yang Guang so they could meet and he pretty much told Yang Guang to fuck off because Ye Limei had to focus on her studies.
I'd prefer it if Ye Limei ended up alone if they're her only options. On the other hand, the police officer looks pretty hot too, I wouldn't be too surprised if he became a love interest soon.