It was simpler once, according to US author and academic Stephanie Coontz. Men and women married for strategic reasons; to consolidate and enhance their lot.

In its essence marriage was a guarantee of “kin” and, when you’re in a highly stratified society “you want to get the most advantageous kin possible.”

Then with the spread of the Enlightenment, says the author in the new Irish Times podcast Off Topic, the idea gained traction that people had the right to pursue happiness in their personal lives as well as in political and economic realms. And so marriage came to be about love.

Men were the first to embrace the "love match" she explained to Off Topic host Fionn Davenport, which had a profound impact on women who were still "totally dependent" on men in economic terms and "struggled" with romantic love.

She describes how letters between women in the 18th century urged each other to love with your “head” because if you “fall in love with a guy who will not be able to support you or with a guy who has all these strong qualities and then misuses them, then you’re in terrible trouble.”

There were also significant consequences for the types of behaviour which came to be associated with the two genders. Ms Coontz thinks this was part of a rearguard action by the social conservatives of the day who fretted about the type of society that might ensure if marriage had its foundations in less concrete principles such as love. There would be nothing to stop people falling in love, running off, having sex and then declaring it all mistake.

Their conclusion, she says was to encourage unions that brought together “opposites” so the reason they had to stay together was because each brought something to the marriage that the other could not, but ‘without which nobody can be a ‘complete person.’

The result as she outlines in the podcast is “men bring strength, they bring power, they bring ambition. Once they were expected to cry openly but then they were kind of stripped of those roles and women who used to be expected to be very hard headed in business, who would wring the chicken’s necks, who would help make the bacon, not to have the bacon brought home to her, and to be very very interested in sex, more prone to sexual error, as the ministers used to say, suddenly they became gentle, weak, and terribly virtuous, and so these kinds of things stabilised the love match for the next 100 years to the extent that men and women began to internalise these traits.”

For women, confusion remained about this new state of affairs. Ms Coontz who lectures across the United States says this uncertainty is palpable in the literature that was being published at the time.

A lot of the eroticism of the love that you find in the traditional romance novel comes from women confusing intimidation with infatuation with women being put in the position of thinking how in the world, I still need marriage but now I’m supposed to love. I still need to obey my husband but now it has to be out of love not fear, and how do I bring this strong - this guy who is stronger, has more resources, is more powerful, he could really hurt me.

“ How do I get him to love me back? So a lot of the intensity of love is based upon fear or mystery. Now that women’s political and economic roles in life are more equal.”

Ms Coontz suggests that a new appraisal of relationships needs to take place. It has to move more in the direction of “negotiation, sharing interests outside the home, sharing the chores and joys inside home.”

Such couples, she says citing a recent study, also have the benefit of enjoying better sex lives.

To hear more from Stephanie Coontz on this and on the icon that is the Irish Pub, LISTEN to the Off Topic podcast. It is available to download or stream weekly.