The idea of romantic love has a long history, but whether or not actual family formation is affected by that idea is a different question. A historiographical tradition in the 1970s tied the rise of romantic love in practice to the rise of modern capitalism and individualism. However, historians now largely believe that romantic love influenced many medieval marriages:
Christopher Brooke shows how important consent and affection was in
medieval marriage, Martin Ingram shows the presence of love in
ecclesiastical court litigation from the sixteenth century and
Kathleen Davies shows that the ideals of family life changed very
little as between the fifteenth and seventeenth centuries (Outhwaite
1981:chaps. 1,2,3). In one of the first syntheses of the new
historical research on early modern England, Keith Wrightson devotes
two chapters to the family, drawing on a very wide range of published
and unpublished sources. He concludes that below the level of
aristocracy, gentry and urban elite "there is no doubt whatever
that...the initiative in selecting a spouse already lay with the young
people concerned" in the period between 1580 and 1680. In the
motivation of those getting married, he can discern no significant
shift in this period (Wrightson 1982:74,79).
The thinking now is that romantic love is most practical in societies with weak kinship systems. This has described England (and likely most of Northern Europe) since Anglo-Saxon times:
Romantic love also fitted with the kinship system ... In
closely-knit, interdependent, kinship-based societies "any
considerable range of affective spontaneity would tend to impinge on
the statuses and interests of too many others, with disequilibriating
consequences for the system as a whole" (Parsons 1964:187-8). When
wider kinship is strong, marriages are arranged and affection between
husband and wife is a secondary force. As Sjoberg has written,
"Romantic love is, of all things, an expression of individualism, and
as such it is at variance with the maintenance of a well-integrated
extended kinship unit" (1960:153). . .
We now know
that the cognatic kinship system which isolates out the husband and
wife in terminology and residence was present in England from
Anglo-Saxon times onwards. There is little evidence that wider kinship
groupings were important in everyday life among the mass of the
population. Romantic love was an appropriate ideology which could both
flourish and hold together this individualistic system.
To the extent that modern capitalism has encouraged an even greater development of the "nuclear family," the tendencies of all cultures toward romantic love have also grown more noticeable.
Again, this isn't to suggest that the idea of romantic love is particularly Western or modern. Rather, the influence of romantic love on actual family formation is determined by economics, politics, and other kinship patterns. Love therefore becomes manifest in unique ways in each culture. As Alan MacFarlane puts it:
The biological urge to mate, based on a deep attraction between males
and females is universal. But the way in which cultures encourage,
use, or discourage it varies enormously. In the majority of societies,
the feelings have not been encouraged, marriage and individual
sentiment are not connected, and marriages have been arranged. This
has made it possible to maintain the cohesion of wider groups of which
the individual is not a separated part. Something about the kinship
system in parts of Europe, and the way it interlocked with politics,
economics and religion, gave the biological drives a great deal of
freedom. Indeed the economy and society seemed positively to stimulate
the natural emotions.
Source: Alan MacFarlane, "Love and Capitalism"