I've seen a lot of cracks in a lot of relationships. Some people are lucky or pig stubborn enough to make it work until they die, but that's a hell of a thing to ask of anybody to commit to someone for (if we're talking on my scale) decades when you don't even know who you're going to be in fifty years, let alone who the person you marry is going to be. You need to be compatible, or at least fit okay together, in so many ways.