The secret for long relationships is not having a perfect and harmonious love affair. It is not how less often you fight, not because of the number of similarities and the stuffs you both like doing together nor the number of mistakes you did. Those things count but it is the faith that keeps you going. A relationship would last if both of you are willing not to give up, if both of you is willing to stand up and still try every time one of you or both of you fall. You should not lose hope when you are struck with problems along the way. Give each other hope and hold on as long as you can.