When you go through the stages of love the make or break for most couples comes after the honeymoon phase goes away. During this time you start to learn the nitty gritty about the person you love. And this is where the conflict can start to arise.
Learning everything about someone isn't easy because it also forces you to look deeper within yourself and evaluate if this is something you can both grow through to better each other and the quality of your love. Each relationship comes to the stage where you put yourselves through the fire and whether or not you can handle the heat will ultimately decide how this love will transform.