The relations at which the man and the woman have no right to change each other are called monogamous. They as though conclude the agreement according to which they undertake to be loyal.
Why the monogamy became social
Family, and it not for nothing is considered a cell of society, keeps just on the monogamous relations. Moreover, the monogamy as scientists-evolutionists consider, became one of the reasons for which the person became orthograde.
History developed as follows. Primacies, far ancestors of the person, met for the short-term relations after which the female remained with posterity, and the male moved off in searches of the new relations. But some couples became attached to each other stronger, then the male remained with a female and helped it to care for posterity. He moved off in searches of food and when found it, brought to the family. But it turned out that in a mouth it is possible to bring very little, and monkeys then ran on all four paws. Then some males guessed to bring livelihood in then yet not issued "hands", moving on the lower extremities.
The monogamy was fixed in traditional western society very strongly. Even today, when women are able "to get livelihood", even when children still small, more often these cares fall on the father. At the same time surely it is meant that family monogamous. Otherwise why to the father to care for foreign posterity? Such approach strengthened monogamy positions in the ancient time though now quite often it happens that the man accepts other people's children as the. But also today the monogamous relations are considered as ideal for education of children. Nevertheless, in east countries the men are allowed to have several wives as the Moslem allows such state of affairs. In the countries with the western mentality (Europe, America and Australia) only one partner in marriage is resolved, and it is frequent even is fixed legislatively.
Look of psychologists
In spite of the fact that the monogamy is the standard way of creation of family, unfaithfulness among spouses is very widespread. Psychologists consider that people have to "ripen" for the monogamous relations, and it is difficult. The fact is that people can quite have deep feelings to one person, at the same time sometimes "being fond" of someone else. Hobby quickly takes place, but during this period the probability to make treason sharply increases. Happens and so that the person changes in the heat of passion, for example, during intoxication. Fix much less often cases of long-term treason when the person has the partner in marriage and one more, illegitimate, throughout long time. The fact is that feelings of people – a complex and tangled system, sometimes quite contradictory. Not everyone can resist the charming representative of an opposite sex even if there is a permanent partner. Some people have low moral foundations, they do not even try to resist, sometimes even specially hunting for illegitimate "adventures". Also those who that the monogamy is opposite to human nature are sure. Such people get the relations, in advance agreeing with the partner on such deal. It is impossible to call similar marriages traditional, but sometimes they exist quite successfully. Similar approach to the relations is called polygamy.