单项选择题

Romantic love is a culture trait found primarily in industrialized societies. Elsewhere in the world, pragmatic considerations rather than flights of fancy are often used to make a choice of partner, and romantic love is seen as an unfortunate inconvenience that gets in the way of the ordinary, rational process of mate selection. Traces of this attitude persist in the American upper classes, where daughters are expected to marry "well" —that is, to a male who is eligible by reason of family background and earning potential. Most Americans, however, see romantic love as essential for a successful marriage, and tend to look askance(轻蔑地) at anyone who marries for a more practical reason in which love plays no part.
The phenomenon of romantic love occurs when two young people meet and find one another personally and physically attractive. They become mutually absorbed, start to behave in what appears to be a flighty (充满幻想的), even irrational manner, decide that they are right for one another, and may then enter a marriage whose success is expected to be guaranteed by their enduring love. Behavior of this kind is portrayed and warmly endorsed (赞同)throughout American popular culture, by books, magazines, comics, records, popular songs, movies, and TV. Romantic love is a noble ideal, and it can certainly provide a basis for the spouses to "live happily ever after". But a marriage can equally well be founded on much more practical considerations—as indeed they have been in most societies throughout most of history. Why is romantic love of such importance in the modern world The reason seems to be that it has some basic functions in maintaining the institution of the nuclear family(小家庭).
According to the passage, most Americans ______.