You seriously believe that a 25yrs old woman won't marry a 45yrs old man due to fear of changing adult diapers?
First off, unless she's a virgin, whatever she says on the subject doesn't matter ... she couldn't hold a relationship for a few years, yet she worries what will happen with her husband in 35yrs time? It's ridiculous.
Secondly, while on the surface it might look like a reasonable concern, in reality it's looking at the future through a negative lens. Life is full of risks, and while a husband of the same age will statistically have a lower chance of needing adult diapers than a husband 20yrs older, you never know what the future holds. You can't start a marriage based off statistics.