History is far more complex at any given moment than we might imagine.
For instance, the narrative "once upon a time men domineered women" is far too simplistic. The truth is, in many ways, the romance writers are right: couples were far more variable in the past than a one-size-fits-all description.
It is factually and culturally true that women had far fewer rights until the mid-to-late twentieth century than at any other time in history (the myth of the perfect matriarchal society notwithstanding; even matriarchal Native American societies still functioned with men as the people who killed the most meat and waged the most wars though there were Native American female chiefs and war leaders).
Women are in a far better position now--despite what the doomsdaying types try to preach--than ever before. No longer being tied to one's biological fate changes everything.
However, assuming that only modern couples have variety misses the mark. This assumption falls into the same category as the highly ridiculous argument that "people in the past didn't love their children as much as we do." As Antonio Fraser shows in The Weaker Vessel, yes, actually they did. And they were as varied in their responses to sex, control, argument, future goals, etc. as we are.
Marie and Pierre Curie lived in a time when it would be expected, even encouraged, for a man to take sole credit for his and his wife's work (and Pierre Curie was told as much by his friends). And yet he insisted that he not receive the Nobel Prize without her.
Were the Curies also products of their time? Yes, they were. For one, in the above image, they are wearing the dress of the time. I'm not enough of a fashion expert to know if their dress is formal or informal, avant-garde or conservative. The point is: they are a unique couple within their time period.
We current-day products also act uniquely within the confines of our understanding and human/cultural limitations. Being bound by the "now" is one reason the future is so hard to predict and why sci-fi tells us more about the present than the future. For instance, do we know what future couples will find old-fashioned and backwards about us--what will surprise them about "relationships back in the good-old-days"?
No. And no matter how much we try, we will probably miss it since it will be something odd and unanticipated that we modern people completely take for granted, like, Couples in the future will think it strange that we put so much emphasis on . . .
taking vacations togetherWho knows?!
doing anything apart
paying joint taxes
having a common household pet
calling each other by cute names
calling each other by first names
In the meantime, it IS still likely that extroverts will marry introverts--or not. Exercise buffs will
marry readers--or not. Passive people will marry other passive people--or not. Depressed people will drive their spouses crazy--or not. Despite all the sociological studies and dating books in the world, it is likely that people will go on being weird and dating weirdly and marrying weirdly.
People will continue to fall in love within a common structure (the time period and culture) while not following a common pattern (a particular narrative arc).