You can plan future if you're old-ish and she's young. Not vice versa.
You're crazy if you think the age difference isn't huge. I'm not "almost 30", I'm 28. Are you aware that she's older 14 years, which half of my overall age? The difference between a mind of a 25yo and a 30yo is like two different planets, let alone 14 years and a 40+ person.
And no. It's not a myth. It's a proven thing.
Why? Neither you nor the others are arguing this reasoning.
We are so naturalized that a man is attracted in all senses by a young girl that when it's vice versa it surprises us, it scares us, it seems abnormal, or we think that a couple like that will not prosper.
However, the problems that may arise in both cases are the same.
I can understand that in your particular case you don't want to have a relationship with a 42yo lady (although you don't have to call me crazy to defend your position

), but I still don't understand your initial comment "Jesus Christ, why do old women think that young men want to have relationship with them?". What future plans can a young girl have with an old man? Change the diapers of her son and those of her old man?
And of course, a woman of that age can have a totally normal and healthy pregnancy. I know that the older she is there are more chances of having problems but there are totally effective treatments. She's not 50 years old.
It would make more sense if you told me that surely she thinks of a family project already and you don't yet, for whatever reason.