Tommaso,i can distinguish false moraliste and who just don`t want to cheat))).Mostly question of betrayance raising when people HAVE to live together,when feelings gone away-if they have children and all that.in such cases some couple live phisically in the same place,but have parallel lifes-it`s understandable,they don`t want upset children.But when couple on the highest point of relathioship only people with mental desease can cheat,i think.