We laugh at the sitcoms when, during intercourse, couples start discussing the shopping list, or on staring vacantly up at the ceiling remember it really does need painting. We laugh because we recognise this scenario. Momentarily we consider spicing up our love lives, planning romantic evenings that'll get the old juices flowing again. But then that hormone gremlin says, "Nah! Can't be bothered. I really would rather have a cup of tea".