What are you talking about, how and when did Aoba ever backstab Nene ? And I don't see her being jealous either. Oo
I'm joking/exaggerating. She went along with all of Nene's suggestions, agreed that the programmer-animator would want the strong pricey energy drink, but when they got scolded for buying that, she suddenly said, "Just like I told you, Nene!" and the latter rightly said "but you agreed with everything!"
Their little bits of being grownup one-upmanship are cute, but that was an example of Aoba being childish. Aoba did say she should get a proper receipt, though, and Nene talked her out of it, so if I'm serious, I'll say most of the scolding was Nene's fault.
I was speaking from Nene's POV :)