The history of marriage is so long that its origin is impossible to find. But we can look at other societies where people live like our ancestors did 10,000 years ago, and then we find that almost all of them have some kind of ritual to publicly bind a man and a woman together as a couple.
Exceptions are found among the Bushmen (a man just takes off with his fiancee and when he comes back into the village they are considered husband and wife), and the Aboriginals in Australia (after her circumcision, the woman has sex with a number of privileged men, after which she joins the man for whom she was destined and together they set up a household). The Eskimos, too, have only a simple ritual around setting up a household. But even in these cases there is some kind of contract between two people of the opposite sex recognized by society.
In the great majority of cultures, marriage is a public affair. It is a contract between two families rather than between two individuals, regulating property and inheritance, rights and social status of children. The personal relationship between partners is only part of the function of marriage. Only recently -since sexual reform started about 200 years ago, has the idea of love as a basis for marriage come up in our society. In fact, however, the same interests are at stake: property, keeping a household together, having children and raising them. So we, too, can understand other cultures, where the choice of a partner is made by the family with the object of exchanging property and ensure continuation of family and cultural values.
Divorce is generally considered a sad event, but it is more likely to happen if romantic love is the main motive of marriage. In that sense, love is a threat to marriage, and has been a very important factor in criticizing this prison-like institution. True love is not a suitable foundation for a long-lasting relationship. On the contrary: those who have ever been in love (which is pure heaven while it lasts) will at some stage long for a repeat performance. The more primitive the society, the less room there is for romantic love. Marriage is almost always a public affair. Even those couples who want to keep it simple, still have to go to a marriage official and bring witnesses. Those who make it a big affair, like the members of a royal family, also submit to religious rituals as well, which are witnessed and celebrated by the whole population.