Another thing that’s hard for me to understand about NFP is this: It’s wrong to separate sex from procreation, but that seems to be exactly what you are doing when you practice NFP. I don’t see how practicing it makes you more open to life when it is actually more effective than most artificial contraception.
On another note, I see on the post after yours to me that you are going to have a baby. Congrats!
The Church teaches that sex is intended to have a twofold purpose, unitive and procreative. You can’t separate them. And they are both essential to the act.
In a truly Catholic marriage, the sex act will always be capable of giving life whether or not life actually comes from it. You are always to give yourself fully and completely to your spouse. The knowledge that life will most likely not come from the act doesn’t negate the fact that you are still giving yourself fully and completely to your spouse. That is what the Church requires, fullness and complete giving.
This never happens when contraception is used. And that’s the difference between the sex act that doesn’t result in life due to actually preventing conception and the sex act that doesn’t result in pregnancy because the opportunity for conception failed to occur.
Baby #4 should be here at the end of the summer. And if uterine behavior is any indication, he should be as wild and crazy as his sisters and brother.