This is, of course, because just as Michael doesn't want to really admit that teachers aren't fun-hating monsters or that he isn't as smart, cool or popular as he'd like to think or especially that people's feelings matter to them even if he can never feel their pain, Elly doesn't want to ever admit that she's a thin-skinned woman who doesn't like it when people disagree with her on any issue any more than she wants to admit to having a victim complex or volcanic temper. Her need to mentally edit out all the times that she escalated instantly from normal person to raging maniac the instant someone displayed the least bit of a difference of opinion means that she can't learn from the past because she blinds herself to all the times she made a big deal out of something that she later realized wasn't.
This, I think, is the reason that isn't "not wanting to look weak lest they destroy her" that she never apologizes for turning into a huffy maniac screaming about how she's not going to get angry. She remembers herself as being calmer because she always resented her mother for describing her as always trying to pick fights because she needs to feel angry and hurt to feel good about herself. It doesn't make sense to Elly that she's this angry person who wants to feel victimized and mistreated all the time because that doesn't sound healthy.