Comparing the Holy Family to NFP seems sacrilegious to me. The big difference, first of all, is that, as her name implies, the Blessed Virgin Mary was a VIRGIN. St. Joseph also was celibate, at least during his marriage to Mary. They didn't have sex. Virginity is a higher calling. But users of NFP want to have sex but just not have children, thus frustrating the nature and purpose of the conjugal act.
Here's a simple suggestion: any Catholic couples who feel they have grave reasons to avoid conception could simply imitate the Holy Family and avoid all marital relations until they are ready once again to conceive. This would completely eliminate the need for thermometers, beads, charts, graphs, etc.
You can't really mean this, since frustration of the nature and purpose of the conjugal act is intrinsically evil, per Pius XI, and therefore can never be permitted.
Rather, not having children by use of NFP is problematic because of the failure to fulfill the duty owed to society of propagating the human race. This has to be separated from the malice involved in contraception, just as Pius XII does:
The matrimonial contract, which confers on the married couple the right to satisfy the inclination of nature, constitutes them in a state of life, namely, the matrimonial state. Now, on married couples, who make use of the specific act of their state, nature and the Creator impose the function of providing for the preservation of mankind. This is the characteristic service which gives rise to the peculiar value of their state, the bonum prolis. The individual and society, the people and the State, the Church itself, depend for their existence, in the order established by God, on fruitful marriages. Therefore, to embrace the matrimonial state, to use continually the faculty proper to such a state and lawful only therein, and, at the same time, to avoid its primary duty without a grave reason, would be a sin against the very nature of married life.
Otherwise your reasoning will be unable to distinguish at all between the practice of periodic continence and the use of contraception, leading either to approval of both or the condemnation of both, conclusions which are ruled out for us by the authority of the Church.
I didn't make that comparison at all. I pointed out that your false choice of sterility versus unlimited fecundity in marriage also condemns the Holy Family. You may not like that, but, well, there it is, because the Holy Family did not choose unlimited fecundity.
But users of NFP want to have sex but just not have children, thus frustrating the nature and purpose of the conjugal act.
The conjugal act has more purposes than the conception of children, otherwise it would only be licit for conceiving children, and would be illicit when one cannot.
The path you are travelling down condemns couples who have sex once the wife is already pregnant or after menopause or after a licit operation causing sterilization (i.e. removal of cancerous generative organs). Where do you find such a harsh attitude in the teaching of the Church?
You seem very upset at the thought of couples using their marriage without a probability of conception. But this is no different than the use of marriage when pregnancy is definitely impossible in the cases I listed above. If you do not condemn the use of marriage in the cases above, then you cannot condemn those who justly limit their use of marriage to infertile periods. There is certainly no difference in the act, means, motivation, or end in the case of sex during pregnancy or after menopause and the use of NFP.
Your serve Max.