“Getting married requires a radical and permanent reorientation of attentional habits. When a child is added to the pair, both parents have to readapt again to accommodate the needs of the infant: their sleep cycle must change, they will go out less often, the wife may give up her job, they may have to start saving for the child’s education. All this can be very hard work, and it can also be very frustrating. If a person is unwilling to adjust personal goals when starting a relationship, then a lot of what subsequently happens in that relationship”