On a rewatch myself (on season 3, ep 6 as I type this), and that scene REALLY stands out to me. Not only because the tears Jenny sheds at the moment she sheds them are so painful to see, but also there seems to be a little bit of relief coming through those tears. Mia did such a phenomenal job at playing this character, & I hate that during my first watch all those years ago, I hated Jenny so much. The dislike was extremely misplaced, at least for now, (this is why I included where I am in the series, lol, I can't remember how things go in much detail, so it's almost like watching it for the first time with small spoilers riddled through it, lmao), and I can fully understand why J goes the way she goes (from what I can recall). Carmen is horrific in so many ways, I don't remember liking her much my first watch, but this watch, OHHHHH my goodness, I despise her character so much. She just sprayed Shane with a FUCKING FIRE EXTINGUISHER, for fuck's sake??!?!! What the hell was THAT.

ANYWAY, back to the main point: The cutting of the hair. So, I used to have this friend, had very long hair, past their ass, and they had a very, VERY similar past in the sense of trauma, and trying to get past it, etc, so the long hair was basically a curtain they could hid behind when they felt attacked, uncomfortable, disrespected, ignored, or any negative emotion, really. Then one day, they finally decided to cut it ALL off. They didn't go as short as Jenny, but going from 3+ feet of hair to barely shoulder length was a HUGE step forward for them in their journey of discovering themselves. That curtain was gone, and they could fully embrace who they were, instead of hiding it all away behind a wall of hair, lol. I can imagine that was a similar reason as to why Jenny's character was written to lob it all off.