Writer goofs. She removed the birth control, proving the conspiracy to her husband, but he later totally forgets the incontrovertible proof. Doesn't mention it to anyone, even in an effort to save his wife. It proves everything she is saying or at least strongly corroborates it... definitely explains why they fail to have children but the husband continues to be unaffected by it. Magic of Hollywood? ..a glitch? Or the writers creative arrogance the audience won't notice?