That time in s1 e3 she lost the don’t stop believing part to Quinn must’ve really really hurt, she just got rejected by Finn for Quinn, Quinn bullies her a lot and she generally feels like she’s worth less than her and then Schue gives Quinn the part she sung very successfully. He also says in that scene that „not everything is about you“ and that he isn’t punishing her, but two seconds prior he said that she made this happen because she lied to him with the assembly song. The cherry on top is that he also insinuates that Quinn is better or on par with her singing which is basically the only thing Rachel considers better than her about herself.

Edit: I actually like the two seconds we get from Diana more than any other version, I’m just talking the emotional and social aspect.