For studying the history of love, meaning for "love" the representation of the most famous feeling which connects men and women, as well possibly all the people who share daily life in a social space, sociologist Fernando Henriques's book "Love in action" is a source that we cannot ignore.
We just take a suggestive sample of his open minded and fertile analysis, from the chapter IV.
"If we define love as a prolonged and mutual attachment both sexual and spiritual between two people, we find that it is sometimes considered as primarily a European phenomenon. Romantic love in Europe appears to have been unknown prior to the appearance in late eleventh century France of the troubadours and trouvères. That is not to say that attachments of this kind did not exist between individuals before that time, but that it was not accepted and formalised as a popular conception. For example, the emphasis in the Norse Sagas is almost entirely on heroic deeds and adventure. Heroines are formidable women who would not be guilty of lukeswarm, feminine passions - they are admired for male qualities. This is in marked contrast to the essential erotic element in Provençal poetry of the following centuries.
The overwhelming emphasis on sexuality and sexual passion which is characteristic of the pagan literatures of Europe, particularly the Irish, is not evidence for the existence of romantic notions of love. For example, the picture which emerges from Celtic literature is a society devoted to sexual pursuits but paying very little regard to the relationships between individuals. The incident in the Feast of Bricriu when the hero Cuchulain and his followers, who are being entertained by the King of Ulster, are offered fifty women each for their sexual needs - the number includes the Queen and her daughter - can be regarded as typical of Celtic ideas of love".