Given the custom of sleeping in the same bed, couples must be more interested in resolving disputes before the evening than two friends might be. Who, but the strangest of persons, would enjoy being in an intimately close and vulnerable position with their partner when they hadn’t yet put an earlier argument to rest? Or, maybe each partner longs for night to come because their physical attraction to one another is such that a bit of fucking will put things right. The bed heals all wounds, angry sex is the best sex, etc. It’s naive to believe that a couple’s sex life could remain healthy, unscathed by any persisting disputes that might arise between them, though such a relationship would be interesting!