Oh, I hate that!
I read a novel recently, where it quickly became apparent there was “somethng wrong” with one of the main characters. It was never specified exactly what, but they were out hiking, and she was getting tired all the time, and having trouble getting over stiles, and that sort of thing.
I thought: “Oh Gawd, this sounds familiar!”
Worse still, it then became apparent she was going to DIE, and her male companion (whom we’d assumed was her husband/boyfriend) was in fact some sort of carer, or perhaps her spiritual advisor.
The book got tedious for unrelated reasons (whole chunks in archaic regional dialect, that was virtually incomprehensible), but I probably never would have started it, if I’d thought it was going to be all about somebody dying of [UNNAMED ILLNESS], that seemed to have an awful lot in common with MS…