I think the real problem is not really "falling out of love" but it's the person. It is the person's character that is the real problem. Love is a "commitment". You don't love a person when you feel like it and when you don't, you just quit. That's not how it's supposed to be. If both of you are matured enough and know what is right, you can have a lasting relationship because you know how to handle things in your relationship. Nobody is perfect and no relationship is perfect. You just have to know how to settle problems when they come. Quitting is not a solution to a problem. Relationship is to be "built" , not to be "destroyed".