Rosalie is 50, her husband, 30 years old. Rosalie reached her prime when she indeed was 30 and it lasted up until she hit 40 and gained seventy pounds. It was the only thing she could do to have peace.
Rosalie, it seems, was sexed out. Her mistake was in marrying a man twenty years younger, a young stallion whose only achievements in life were making tons of money and making love five times each (and every) night.
Which was fine for ten years then took its toll on poor Rosalie, who didn't have the stamina of a whore but whose younger sister Mary had in abundance.