Unlike novels, most people can only live an ordinary life. A lasting partner and love are hard to come by, and you are lucky enough to be able to walk with your loved one for a while. Many times the end of a relationship does not mean the elimination of feelings, but the time and place are wrong. Maybe the person who can walk through life with you is not the person with the deepest emotional entanglement with you, but the person who appears in the right place at the right time.
Purpose: The love of a lifetime is hard to come by, and you are lucky enough to be able to walk together for a while.