Is it wrong for me to accept the very real possibility (in light of social trends in the past decades) that my current partner and I might well break up, for reasons yet unforseeable, in the future? It seems a rational judgement - a large number of marriages don't last, and unmarried partnerships even more so - yet I can imagine that I would be upset if my partner accepted this possibility as one of those "facts of life" we have to deal with.