She should finish it, I think. The series negatively affected my mood at times. I could only bring myself to watch one to a few episodes per week ~ month, even. Stopping frequently, analysing assertions, and thinking about hard-to-process bits for long stretches at a time kept me occupied for the better part of more than a year. In the end it strengthened my ability to safely process uncomfortable ideas. Shortly after viewing the denouement ever-pervading thoughts about the series were silenced.

In brief, mental security may be better served by watching the series in its entirety; I think stopping mid-way a potentially worrying decision.

Only potentially, of course. She probably forgot about it already.