this is well thought out and probably the most accurate reasoning.

I think it's probably what you most want to hear because it excuses her and means you don't have to face up to harsh realities. For me, the above scenario, while it helps you understand what she might have been feeling, does not excuse her behaviour for a second.

A good response to a situation like described above would be to at the time of leaving apologise to at least you and maybe your friends for feeling so tired and needing to go home, and then would be saying afterwards 'Ah hey /u/GoogleFloobs, sorry I screwed up your catch up time with your buddies, and they seem cool, but I just couldn't handle it any more'. The idea that she is the one that gets angry is ridiculous - she made herself angry with poor communication skills/by not dealing with her feelings as they built up, and there is no real excuse for anger here.

At the best, the way she's carrying on is a poor and immature style of communication, at worst it's signs of abusive behaviour. This sort of thing happens all the time in abusive relationships - it's liking walking on eggshells because you never know when suddenly they're going to turn angry at you or make a scene in front of your friends. You stop hanging out with your friends because it's difficult/embarrassing and you can't deal with how she gets angry about not coming first. I've been in this position and it's not as obvious what is happening as you might think, but it is a classic path that abusive relationships head down.

The texts are another matter altogether. There are so many texts she could have sent you, even though she in my opinion doesn't have any right to be pissed off. 'Disappointed about tonight, thought you would take me home sooner after I said I was tired' would be one thing, but what she sent is fucked up and NOT NORMAL - it's a huge red flag.