My wife used to mock me for being adamant about 120hz+ monitors, until the day I had her try my 200hz monitor for an entire day.
Her eyes were much less tired at the end of the day.
I read similar reports so many times, when I got my 165hz screen I got disappointed. I also disable it on my phone to get more battery life. Different folks, different strokes.
Does she use f.lux on her usual rig? That saved my eyes like 15 years ago whenever I found it and that was on the low dpi screens to boot. Make sure you use the setting to match it to your lighting conditions.