Simon May in the FT says that romantic love helps to fulfill "the ambition to subvert traditional relations of class, power and more recently gender."
Traditionally, he's been right. From Cinderella to Rosie M Banks, a staple of fiction has been how love can conquer class divides.
But no more. Love now helps reinforce the class divide. As Jeremy Greenwood and colleagues point out, the rise of assortative mating - the rich marrying the rich - has been a significant cause of increased inequality.
Assortative mating can also perpetuate inequality through the generations - partly because the child of rich parents is more likely to marry someone rich, but also because being born into a family with two wealthy, educated parents might increase one's chances of doing well in life, because educated mothers make for educated children.
However, assortative mating hasn't increased because of a conspiracy among the rich. Instead, I suspect, one big cause has been job polarization. In the 60s and 70s, men commonly married secretaries or someone from the typing pool. Today, these opportunities have vanished with the decline of secretaries and typing pools. In this sense, assortative mating has increased because it's the only game in town - a fact reinforced by the increased economic status of women since the 60s.
This helps explain another trend since the 70s - for marriage rates, here (pdf) and in the US, to decline. As Sam Pizzigati says, "social interactions across income levels have become considerably rarer" - which reduces one's chances of meeting "the one."
I say all this for two reasons. First, what we have here is an example of Marx's dictum: "The mode of production of material life conditions the general process of social, political and intellectual life." As the mode of production changed to eliminate secretaries and typing pools, so cross-class marriages have declined, and with them marriage rates overall.
Secondly, class divisions can perpetuate themselves not only by generating ideologies which sustain inequality, but also by generating practices such as assortative mating which themselves contribute to inequality.