When I went thru RCIA & converted to Catholicism, we had a couple of long classes re: marriage/ annulment/ divorce.
We read all the Bible passages already mentioned in the OP, plus several others.
One that stuck in my head was “Render unto Caesar that which is Caesar’s, and to God, that which is God’s.”
The Deacon leading the class said, “Jesus wasn’t only talking about gold coins. This applies to everything having a divine & worldly aspect, including marriage. We Catholics call it HOLY matrimony because it must be rendered unto God.”
He went on to explain that signing the marriage license & filing it in the courthouse is only about property & inheritance rights; the *real* marriage is the sacramental one.
THEN he explained that this courthouse stuff is tied to the worldly notion of “illegitimate” children, but in God’s eyes, no child is illegitimate, regardless of Caesar’s approval or not.
He said the idea of a need for abortion is rooted in the idea of marriage being a mostly property arrangement, and divorce as a casting off of the wife as if she is disposable property; women shamed for out of wedlock children came to regard those “illegitimate” children in the same way, disposable. But God does not regard us as Caesar does. We are worth so much more to God, and we must foremost honor God as we act accordingly toward spouse and children.
Anyway, your comment about “secular half-hearted promise.. in Vegas or the courthouse”
reminded me of the “Render unto Caesar” passage.
Sorry for the rambling.