It was a weird day for her even before stream started. She drove in the rain, had to start stream late, lightning/thunder was scaring her on and off through most of the stream. Today's stream attracted a few weirdo rulebreakers for whatever reason, which is kinda unusual and probably didn't help considering she was already out of her comfort zone because of the weather (etc). Everything stayed on good energy until she got pretty hard stuck at one of the bosses, which led to a progression we've all seen before. Chat mostly being encouraging, some people getting frustrated/backseaty, the streamer going through the whole progression of gamer frustration.
She seemed to be in a pretty good spot, slowly making progress on the fight, when she decided to take a bathroom break for a short breather. Ami always checks her maros during bathroom breaks, and this time someone sent her something she only described as "cruel." Whatever it was, it really got to her - she was audibly upset and decided to end the stream there. I think she also blames herself for having let it show how much it bothered her, which I'd agree was probably a mistake. Apart from the inevitable one or two retards, the audience at least appears to be handling it well.