Do you have any idea how many men have cherished specific women, just begging for the opportunity to care for them for life, and been rebuffed?
That may or may not be necessary, but it sure generally is not sufficient.
I would agree with the notion that one-way longing for a woman is likely quite common, although I am less sure anyone has a count, particularly a count where we know how sincere this cherishing is. Knowing one's own heart is a tricky thing and when put to the test one may find the woman a man thinks they cherish is not really the person that woman really is. It may be something about her that is in the perception.
Also I have the notion that it is quite common that women will be deceived by men who proclaim such feelings and do not follow through with them. And thus it is not surprising that they may often err on the side of caution and tragically miss-out one someone who would be true.
Of the men that deceive women, some may be deceived themselves to some extent or another as to how sincere their feelings would lead to being true if given the chance. Others may be cold hearted manipulators. And some may be somewhere in between--men who if they were honest with themselves would not obsess over the particular woman--who love a fantasy picture life with her rather than the real person.
Also seems I left the "take care of" as a bit equivocal. What I have in mind is in the context of biological strategies programmed into the natural mate-choosing side of the female brain. A man whom she perceives will stay and take care of her and their children. Who protects them from dangers. Provides resources. And so forth.
Of course females also desire men that have good traits of health and intelligence etc...but that of course is correlated with the man's ability to care for her. Also wealth and power within the social structure are also correlated with it.
There is more going on in the equation--there is the far less just and ethical reproduction strategies that are built into the brains of both genders. A woman might be tempted into betraying the man taking care of her and her children for a fling with a man whose physical or mental traits impresses her. And obviously there are men who would be tempted to go along with her in this behind his back.
But within the bounds of just and ethical behavior, the critical thing is finding a someone where you can be true to each other.