Must the questioner inform his future wife that he had a large cold sore (herpes simplex), perhaps herpes, knowing that it appeared only once and then disappeared, and that a dermatologist later diagnosed the condition as eczema?

You are not obligated to inform your fiancée about your past exposure to a stye or similar conditions, as long as their effects have disappeared. However, if you are certain that you have contracted herpes, you must inform her, as it is a contagious disease that requires disclosure before marriage. If she accepts, that is her decision; otherwise, seek someone else, or treat yourself until you are cured. In that case, you will not be obligated to inform her about your previous infection.