Inheritance.
Due to inherit a fortune when his sickly, widower father dies, Charles decided he needed a woman to enjoy it with. Going to a singles' bar, he spotted a woman whose beauty took his breath away.
"I'm just an ordinary man," he said, walking up to her, "but in just a week or two, my father will die and I'll inherit 20 million dollars."
The woman went home with Charles, and the next day she became his stepmother.