I’m not at all interested in contraception, but I’d like to fully undersrand the topic.
It’s probably a semantic argument you’re getting caught on.
Contraception obviously isn’t unitive since you are rejecting your spouse’s fertility, and in the case of certain ones there is physically a barrier preventing unity.
Don’t conflate the unitive function of sex with the procreative function - which is what you’ve done here.
They’re two separate things. I’ve not seen anything showing that contracepted sex is observably any more or less unitive than non-contracepted sex.
However, when it comes to the pro-creative aspect, why are natural methods of postponing better than artificial methods?
Honestly? The difference appears to be bald fiat.
The goal of either is “have sex! …but avoid making babies”. Outside of the traditional Catholic paradigm, that’s what “contraception” means. Ergo, NFP is contraceptive just like The Pill is. It just doesn’t use artifice to achieve the end and because of that, some folks think that somehow makes it sufficiently “open to life” in a way the pill isn’t (and despite The Pill and
perfectly executed NFP having nearly identical “failure rates” per pro-NFP literature).
The rationalists watching the display from outside the fence are left scratching their heads; virtually without exception.
Both have the same goals, and since God is all powerful, neither can prevent a child if God wills one.
As you “see” the problem, your primary solution - if you want to remain a devout Catholic - is to try and un-see it.
Best of luck with that.
[Note: While NFP may not use artifice in the same way The Pill does to achieve contraception, perfectly performed NFP almost certainly requires the employment of ovulation kits so that ovulation may be as precisely timed as possible. This is, of course, the use of an artificial object in making NFP work.
Which complicates matters; but I don’t think you need my help to point that out.]