question:  Why isn’t Charles satisfied with the beautiful woman’s reason for having a romantic interest in him?
context: There should be an epitaph for every man, big or little, but a really grand and special one for Loner Charlie. She was blonde to perfection, exquisitely shaped, and the rich promise of her body was exposed to his view. A year ago she had been unattainable, a face to conjure with in erotic dreams, far beyond his ken. He touched buttons by the edge of the bed and the illumination quieted to a soft glow, wrapping her in a radiant halo. New York lay quietly below him. It was the hour of indecision when day has not quite made up its mind to leave and night has not yet attacked in force. She had given of herself freely, warmly, and Charles had accepted. She would have given herself to any man— His thoughts beat a rapid crescendo, activating emotions, stimulating sensations of angry rage. Charles picked it up and folded it across her now cold breasts. Buildings were taller, men were healthier, most of the problems of humanity seemed licked, or nearly so. Life was fun, just a bowl of cherries, until...." The largest cotton crop ever was forecast and rumors from Mexico had it that no one had died from scorpion bite in several weeks. A month later the meat animals, the birds and the household pets began dropping as rapidly as the flies which had dropped earlier. Within a year it was obvious to everyone that man was the only animal left on earth. But the lakes full of dead fish caused a great stink and residents along the coasts began to move inland. And now.... "I've got to find out," Charles told himself. Once a year the Bureau issued The Index, an exact accounting of Earth's four billion inhabitants. And again at the age of 10 each child returned to the Bureau for a recheck. It was for this latter recording that Charles had come to the Bureau some twenty-two years before and a friendly guard had let him peep briefly into the computer room.
output:  Due to the plague that has wiped out all of humanity, Charles is the last man on Earth. She had no choice but to be with him.
options:  Due to their total immunity to the plague, Charles and the beautiful woman is are last people on Earth. She had no choice but to be with him.  Due to divine designation, Charles is deemed a prophet. She only wanted to be with him for his prophecy.  Due to the plague that has wiped out all of humanity, Charles is the last man on Earth. She had no choice but to be with him.  Due to disease, Charles has become the last fertile man on Earth, among many living infertile. She had no choice but to be with him.