May married couples continue marital relations after menopause?
Yes. Inscribed by God in the marital act is a bond between the unitive (love-giving) and procreative (life-giving) aspects. Deliberately thwarting this bond via contraception is immoral, because it undermines the sexual expression of marital love by a husband and wife, an expression of love which by its nature is open to the fruit of new life.
On the other hand, when a woman becomes infertile because of age—or either spouse is infertile for reasons beyond their control during the wife’s normal childbearing years—the marital act is still a beautiful expression that renews their marital love. It’s an unfortunate misconception that the Church teaches otherwise. For more, see the Catechism of the Catholic Church 2366-72.