Hello. This post will mention biological aspects of s*x in quite a specific manner. I am sorry to be blunt. I don't know how else to express it. Please try and remember I really am asking in good faith

Please also if you are a man, don't ignore this. I wish men would not refuse to engage with these subjects just because they are a little squeamish. It is very important because it will surely effect your spouse and children too. Also I just want to hear many people's thoughts including men.
1 - natural?I have long heard of NFP as 'working with a woman's body instead of against it'.
This to me seems to be outright false. A woman experiences most s*xual desire when she is fertile, and the least when she is not fertile. I know for me I have essentially no libido on infertile days, and very high libido on fertile days (I am sorry to be so blunt).
In this sense it seems to actively work
against a woman's biology. Because she can 'only' have s*x with her husband when she does not really want it, and she cannot have s*x when she really does want it. So for many women it would almost rule out the ability to enjoy and desire s*x at all.
And not wanting or enjoying s*x is not just a lack of positive experience. It often is actually negative. Because if a woman is not very aroused, frequently her vagina will be too tight (not relaxed - the v@gina consists of smooth muscle), and not adequately lubricated, for s*x to be anything other than painful.
This means that for a significant portion of women, the only person who can ever really experience enjoyable, consistently non-painful s*x is the husband.
Of course I am generalising. It depends on individual women's hormones, anatomy, and the anatomy of their husbands. But it will surely effect every woman to a some extent, and a significant number women to a significant extent, such that it seriously impacts their ability to be intimate with their husbands.
This leaves many women with only three options:
- Always abstain unless you are okay to have a child at that time. This means if you can only support 3 children, you and your spouse may only enjoy intercourse as little as 3 times in your entire marriage (statistically, probably more than that but certainly very rarely)
- Have intercourse which your husband can enjoy, and you cannot. This seems to go directly against the idea that contraception encourages men (or spouses in general) to objectify and 'use' their wife. If the wife is only ever just 'lying there and taking it', is this not dehumanising?
- Have intercourse whenever and get many consecutive pregnancies and many many children (which for health and practical reasons is obviously not always possible).
I have not seen anybody address these biological aspects of NFP. The only time I have seen women address it was in a joking manner, like 'We never have s*x when I desire my husband, and we only have s*x when I don't desire him!' But that's not funny. I think that's terribly, terribly sad.
Many people say to me, well, what did women do before contraception? They suffered. They died. Childbirth has been something like the first or second biggest cause of human death in history, after malaria (depending on how you count it). Also, women hit puberty later - maybe got their period, say, at age 16 - starvation was common and affected fertility and miscarriages. Women were often breastfeeding one or more babies at a time and were therefore not fertile during that time, so women were capably of being pregnant for less of their lives. Finally, they did not have massive families even if they did get constantly pregnant because many of the babies just died. But now we don't accept people dying, babies don't constantly die these days, people aren't starving, puberty hits later, and not everyone does or is able to breastfeed.
2 - effective?Now I have a second question: its effectiveness. It does have a ~99% effectiveness (for symptoms-based) if used perfectly. This assumes, firstly, that you have a regular, predictable menstrual cycle (I certainly never have and can only tell what happened after my menstrual cycle has finished, when I have the full picture). If you do not then you cannot use it. It also assumes you can wake the same time every single day and take your temperature or mucus. Symptoms-based NFP has an up to 25% efficacy for typical use. That is, for 100 average couples using it for 1 year, 25 of them will get pregnant. That is not very effective. And once again, many people cannot use it at all. (lactational amenhorrea - breastfeeding - is more effective but obviously not every women is currently or is able to breastfeed for a significant period of time).
But, let's say, you do use NFP perfectly. You have a perfect regular cycle and you do everything at the same time every day. Then your effectiveness is 99%. This is more effective than perfect use of a male or female c*ondom, or typical use of various pills and hormonal BC. If the point of NFP is that it is still open to life, surely these other less effective methods are also equally, if not more open to life? The intention for all these uses may not be, in any case, to completely avoid children, but perhaps just to delay them, or space them out, for serious health or practical reasons. And one could say that that remaining possible chance of pregnancy is up to God, and if you do get pregnant, you will not have an @bortion but will accept it from God.
I am not saying that nobody should use NFP or that everyone will be fine and dandy with other forms of contraception. But, I am saying that there are unchangeable biological and hormonal differences with people and probably a large plurality of women cannot effectively use NFP and may not respond so negatively to, say, hormonal contraception.
I would like some response to this... the response to my questions has always been awkwardness and confusion. It seems everyone who explained it to me did not even know or consider these aspects of women's biology and I think that is very sad.