Here's an example of chastity (and childlessness) within a saintly marriage: Dauphine (1284-1360) and Elzear (1285-1323), as told by Dyan Elliott in Spiritual Marriage:
"Dauphine and Elzear went on to develop a profound spiritual rapport in marriage, the very cornerstone of which was their mutual commitment to chastity. During the first eight years of their common life, while living in the house of Elzear's paternal grandfather, the necessity of keeping their virginity a secret forged a link between them that certainly would have rivaled a carnal bond for strength. They were subjected to a number of trials. The family was ambitious for heirs and Dauphine's piety troubled them. Dauphine was made to sing and dance, and was decked out in sumptuous clothes. The candles, which Dauphine used for vigils, were likewise removed from her chamber. The grandfather questioned Dauphine closely, worrying that her prayer and weeping inhibited conception. He ordered doctors to prescribe various potions and ointment for her--all of which she privately threw out. As a final desperate measure, he sent the young couple to Marseilles to see the renowned Arnold of Villanova--who, as luck would have it, was himself an ardent Joachimist and very much in favor of virginity from an eschatological standpoint. The remarkable doctor collaborated with the holy couple by contriving a bogus list of explanations as to why the were temporarily sterile. But the relatives were still suspicious. They eventually resorted to planting spies in their bedroom--worldly women who were supposed to report on anything unusual they saw and to encourage them (one wonders just how) in conjugal relations. Finally, Elzear's relatives decided that Dauphine was permanently sterile and apparently made attempts on her life by trying to poison her food.
"In 1307 Elzear came of age and they were permitted to live at Dauphine's estate at Puimichel. This was a blessed release for the couple. Only then did they have the opportunity to shape a household in accordance with their private ideology. The result was a strict rule of life in which chastity dominated as a kind of absolute value. No sexually active persons, whether married or single, were allowed."
Dyan Elliott, Spiritual Marriage: Sexual Abstinence in Medieval Wedlock (Princeton: Princeton University Press, 1993), 286-287.