Nature has in store many penalties when breaking up if we have offspring. I'm sure this is where the vows get most of their significance. If people don't have children, or the children are full grown, the consequences seem to be neglible. Due to the amount of energy we have available to us compared to times of the past, we can weather a divorce and get away from the misery, if misery is what it has become. I'm not so sure misery really is why most people would break up. This atleast hasn't been the case for me or for others I know, most of the time. I think most people who break up just find circumstances they prefer more as time goes on and things change.