Please imagine the following dilemma.
Imagine you are a married devout catholic couple and are both aged 22 and already have 6 children. The natural family planning methods of billings or similar do not really work for the wife due to a genetic medical condition plus infections that can’t be cured due to intolerance for medication, all that makes diagnosing the vaginal mucus difficult and extremely unreliable and she has highly irregular periods.
You have no family to help you and on a single income barely make ends meet and hardly manage the children. The parish priest and the bishop do not care much and promise to pray for you. There is no help really. The local catholic school charges a fortune and you must send your school to a bad state school.
The couple knows that they cannot have anymore children as the family would be in grave danger and it’s not certain the mother weakened by medical issues and exhaustion and sleep deprivation would even survive.
Such a couple is left with no option except to abstain from sex completely. If they have sex they sin because they are not open to further children. If they have sex with a contraceptive they sin. If the woman’s natural family planning method worked for her they would be sinning anyway if they did have sex because they are not open to children. If they were open to having more children but only if the method of natural family planning were to fail and the woman was really confident in her family planning method but decided to space their children indefinitely until menopause they sin anyway because they know that they don’t want children and know her body so well that she won’t get pregnant. How many Catholics just use natural family planning to get to menopause and claim they were not sinning but never admitting they never intended to have further children? In this sense natural family planning is exactly equivalent to using a pill. If they caress and the man gets aroused then he must finish the sex act with ejaculation or else they are practising a form of withholding ejaculation or interrupting it, again sinning. So a 22 year old young couple need to wait until 50-60 years of age when menopause starts to enjoy sex. Good luck to that marriage. Anyone. Whoever says that people living like that in married abstinence are saints are deluded.
If they have sex and are open to children and she falls pregnant they sin again because they know that they would endanger the life of their children by being unable to manage or care for the children. A sleep deprived , exhausted mother could loose her sanity for a second and loose control of a car for instance or not react quick enough.
The catholic teachings about sex are written by naive philosopher theologians who are poets and idealists living celibate virginal lives and they have glorified sexual love to a degree that it becomes something heavenly and incompatible to real practical family life. If Jesus was around to see the burden of inflexibility priests have placed on families he would be saddened. Sexual love cannot on every occasion fulfil the ideal that theologians have demanded of it. Sex is not always at once unitive, procreative and spiritual.
The Catholic Church needs to throw some big money into researching the indicators of ovulation and come up with a method of natural contraception that works for all women. I imagine a blood prick test like diabetics use to measure progesterone and estrogen levels.