They say that you can't choose who you love. I'd suggest that whether to love them wouldn't be an option. You might fall in love, later learn about your SO's diagnosis, and decide you wanted to change yourself to continue to be with them.
However, knowing that you're not personally equipped to deal with these things and that the "object of your affection" might be better off without you is a certain kind of wisdom.
Exactly, I think I might continue to love that person but I don't think I would be equipped to deal with an event such as the author described and then continue to be "sexually" attracted to them. (not sure that term quite captures it but you get the point)
I can't really see how finding a flaw in a person could change my attraction to them (particularly sexually, though I know you said that wasn't exactly what you meant). Especially this flaw--it's not a moral failing. Moral failings are, indeed, distasteful.
If it's 3 hours per year, I can certainly handle that to be in love.
However, knowing that you're not personally equipped to deal with these things and that the "object of your affection" might be better off without you is a certain kind of wisdom.