nobody has mentioned his idea woman

He wanted "a woman who can't do anything very much," which fit the mermaid. And she was mute so couldn't talk back. One might say she was custom made for this particular middle aged married man who was feeling his years. She was uncomplicated, young, and beautiful and didn't require any sort of sexual prowess or squiring around town to night spots. To his way of thinking, messing around with a mythical creature wasn't being unfaithful, which was more than could be said for his wife's flirtations which seemed to be moving into more serious territory. If Lenore hadn't needed to be toted here and there, kept wet and hidden, she would have been flawless, and far superior to dirty pictures. It's no wonder she was deemed an hallucination! But then mermaids always were that to sailors who had been months at sea. Considering how his wife put him down about his age and didn't wear clothes showing off her body at home, I think Mr. Peabody had been a long time at sea, too. :)