What are the motifs in Message in a Bottle by Nicholas Sparks?

Moving on is a recurring idea. Theresa is a divorcee who has learned from the moment her husband left her that she cannot dwell on the unpleasant but must focus on the future in order to provide for her child. Unfortunately, Theresa does not believe this includes romance because few men are interested in a woman who comes with a child attached. When she meets Garrett, Theresa begins to believe that she can move on in romance as well as other aspects of her life.