To paraphrase Jane Austen, it is a truth universally acknowledged that a married man in possession of a vast fortune must be in want of a newer, younger wife. ↗
By taking a second wife he pays the highest compliment to the first, by showing that she made him so happy as a married man, that he wishes to be so a second time. ↗
In Psycho IV, the time is five years after III, and Norman is out of the hospital. He's a married man, and he's finally learned how to love somebody and have natural sex without killing his lover. ↗