In my case the duration was acceptable (I asked for 6 months of unpaid leave), but burnout was telling me I needed out in two weeks. Management wanted me to stick around for two months before taking extended leave. At the time it wasn't an option I was willing to consider.

As for SO, I suppose you could be right about the cancer (they also gave her 3 weeks of time off earlier this year that didn't impact her PTO bank), but even before cancer her job was super accommodating.