With a little care your ring will maintain it's beauty for many, many years. With common sense habits, regular cleaning, and careful storage, caring for your engagement ring is pretty easy. More information about proper care and when it's best to take your ring off to avoid damage can be found here.
Simply wearing your engagement ring while washing your hands is not an adequate way to clean it. In fact, soaps and other cleaners used on your hands can cloud and dull your ring. It should be cleaned periodically to keep it sparkly. Especially gemstone rings with light colored pale gems like white sapphires, aquamarines, topaz and many others will look dull and lifeless if not cleaned at least once a week. Diamonds and moissanites due to their unique internal optical properties and fire will look sparkly for a longer time, but still should be cleaned regularly.