Like many Victorian novels, The Moonstone ends in marriage. But it's far from being a traditional marriage-driven novel – in other words, it's not the romance of the hero and the heroine that drives the plot forward, it's the theft of the Moonstone. This isn't to say that marriage isn't important to the plot; after all, Franklin probably would have let the matter of the stolen diamond rest if he weren't trying to win Rachel back. The novel looks at a lot of different couples, and almost all the characters offer opinions about what makes married couples happy. The Moonstone might end in marriage, but it doesn't suggest that all marriages end in happiness.
Betteredge's account of his proposal to his wife and Lady Verinder's amusement actually reflect a more serious disparity between the social classes: servants and working-class individuals must make decisions about marriage based on "economy," as Betteredge puts it, while members of the upper class can afford the luxury of marrying for love.
Godfrey Ablewhite's series of failed attempts to marry heiresses for their money shows that even members of the upper class occasionally use marriage as an escape from financial trouble.