Again, you have it wrong. NFP is about avoiding artificial means of blocking pregnancy.
Nothing blocks that pregnancy or that union in NFP. Absolutely nothing.
A 59 year old woman in England gave natural birth. We don’t really know any upper limit with God, for Sarah was quite old and past menopause and said:
(From Young’s literal translation)
Genesis 18:11 And Sarah is hearkening at the opening of the tent, which is behind him; 12 and Abraham and Sarah [are] aged, entering into days — the way of women hath ceased to be to Sarah; 13 and Sarah laugheth in her heart, saying, `After I have waxed old I have had pleasure! — my lord also [is] old!’ 14 And Jehovah saith unto Abraham, `Why [is] this? Sarah hath laughed, saying, Is it true really — I bear — and I am aged? Is any thing too wonderful for Jehovah? at the appointed time I return unto thee, about the time of life, and Sarah hath a son.’
Blocking pregnancy is blocking pregnancy, whether it's *natural* or not.
Scripture didn't indicate that Onan used any *artificial* contraceptives.
So the real issue then, is not the avoiding pregnancy, it's just doing it the *natural* way cause that's better, right?
Wrong. If advocating for sex without the procreative potential promotes homosexuality, then NFP promotes homosexuality because it tells married couple to have sex only when they know she can't get pregnant.