Here is what it means: “You will do, for now, and I presume you feel the same way about me. Otherwise we would just get married. But in the name of a common sense that neither of us possesses we are going to reserve the right to swap each other out for a better option at any point.” And if you do not think that is what living together means—as a fully articulated ethical statement—see if you can formulate something more plausible.
