It is easy to think that, but it doesn't translate necessarily with reality. It is not "planning" for an eventual split as much as it is doing something that makes you feel comfortable. For most people, they are content to hope for the best and pretend that that will somehow make it more likely to succeed. In the end, no matter how much you may want a relationship to continue, the other partner may not, for whatever reason. The whole idea that "thinking" that could somehow cause problems is really simplistic and ideal. It is easy to think that you have the world worked out and everything is perfect and that it is YOU that chose well and therefore it is working out... well, reality isn't always that simplistic of a view. If you end up in divorce, despite all your best efforts, you may yet understand. Hopefully though, you will be lucky, and not have to go through such a rude awakening. I assure you though, it happens to many, many people.