The history of the Church’s teaching on this issue of chaste abstinence during the female cycle goes back to 1853. About 1850 French veterinarians realized that mammals have a fertility cycle, and they speculated about humans. (They speculated that the time of menses was the fertile time. They could have been spared that error if they had paid any attention to the biblical rules against the marriage act during menses and then another five days.) Despite the factual error, the issue reached the Vatican, and in 1853 the Sacred Paenitentiary stated that it was morally permissible for spouses to abstain during the fertile time for purposes of avoiding pregnancy provided they had serious reasons and did not engage in immoral activities during the time of abstinence. The issue as raised again in Spain, and in 1880 the Sacred Paenitentiary reaffirmed its 1853 statement. In Casti Connubii Pope Pius XI not only condemned contraceptive behavior but also mentioned “virtuous continence which Christian law permits in matrimony when both parties consent…” (n. 53. Dec 31, 1930).
With regard to intent, I cannot think of any action, physical or spiritual, that cannot be made bad by a bad intention. That’s why it is important for dioceses and parishes to require that NFP instruction provided under their auspices should include Catholic moral teaching including the call to generosity. NFP instruction that is essentially just an amoral organ recital is seriously deficient.
John Kippley