And the "other" Lenten fast?

From a bishop who knows his history:

'...The Roman Catechism (Catechism of the Council of Trent, 1566), which advised frequent abstinence from marital relations during Lent. “As every blessing is to be obtained from God by holy prayer, the faithful are also to be taught sometimes to abstain from the marriage debt, in order to devote themselves to prayer,” the catechism taught. “Let the faithful understand that this religious continence, according to the proper and holy injunction of our predecessors, is particularly to be observed for at least three days before Communion, and oftener during the solemn fast of Lent.”'

And, of course, from our Orthodox brethren:

"The Marital Fast
Married couples are expected to abstain from sexual relations throughout the Church's four fasting seasons, as well as on the weekly Wednesday and Friday fasts. (This aspect of the fasting rule is probably even more widely ignored, and more difficult for many, than those relating to food. In recognition of this, some sources advocate a more modest, minimal rule: couples should abstain from sexual relations before receiving Holy Communion and throughout Holy Week.)"

And from the Great Lent at Saints Theodore:

"Keeping Lent means much more than just refraining from certain foods. Married couples refrain from sexual relations in order to devote themselves more to prayer. This is why weddings are not performed during Lenten periods."

Oh, and Saint Paul (1 Corinthians 7:5)

Do not deprive one another, except, perhaps, by consent, for a time, that you may give yourselves to prayer; and return together again, lest Satan tempt you for your incontinency.