In Central America, especially in Honduras, usted is often used as a formal pronoun to convey respect between the members of a romantic couple.
Deviations from this norm (more common in Spain than in the Americas) are called "leísmo", "loísmo", or "laísmo", according to which respective pronoun, le, lo, or la, has expanded beyond the etymological usage (le as a direct object, or lo or la as an indirect object).