Pope Paul VI made some excellent points in Humanae Vitae about married love.
Essentially married love is fully human, total, faithful, and fertile. In
today’s society, and sadly even among some Christian groups, such a position is
radical. And radically needed.

From Humanae Vitae
(emphases mine):

[Married] love is above all fully human, a compound of sense and spirit. It is not, then,
merely a question of natural instinct or emotional drive. It is also, and above
all, an act of the free will, whose trust is such that it is meant not only to
survive the joys and sorrows of daily life, but also to grow, so that husband
and wife become in a way one heart and one soul, and together attain their
human fulfillment.

It is a love which is total—that very special form of personal friendship in which
husband and wife generously share everything, allowing no unreasonable
exceptions and not thinking solely of their own convenience. Whoever really
loves his partner loves not only for what he receives, but loves that partner
for the partner’s own sake, content to be able to enrich the other with the
gift of himself.

Married love is also faithful and exclusive of all other, and this until death. This is
how husband and wife understood it on the day on which, fully aware of what
they were doing, they freely vowed themselves to one another in marriage.
Though this fidelity of husband and wife sometimes presents difficulties, no
one has the right to assert that it is impossible; it is, on the contrary,
always honorable and meritorious. The example of countless married couples
proves not only that fidelity is in accord with the nature of marriage, but
also that it is the source of profound and enduring happiness.

Finally, this love is fecund [i.e. fertile]. It is not confined wholly to the loving
interchange of husband and wife; it also contrives to go beyond this to bring
new life into being. "Marriage and conjugal love are by their nature
ordained toward the procreation and education of children. Children are really
the supreme gift of marriage and contribute in the highest degree to their
parents’ welfare.