But the couple in this sort of case is quite different your cases. They have health issues that make pregnancy dangerous or make serious disability likely in the child, but they are able to consummate (unlike the permanent impotent) and they have sound minds and are able to consent to marriage (unlike the person with psychic incapacity), and there’s no permanent intention against children.
Having a good reason to avoid pregnancy throughout the entire marriage does not make the marriage ordered toward procreation any more than a medically justified non-show can win a medal at war or in a sports event. A good reason does not deal away with the absence, it only corroborates it.
If an argument is made that they have no other option, than that should be regarded on par with incapacity. One can’t really have a cake and it eat too and say: ‘oh, I can marry because I’m capable of having children, I just have a good reason not to’ and also say: ‘oh, I don’t have an intention because see, this particular reason forces my hand so I have no choice’.
Being firmly decided and having a pact to rigorously avoid conception for the entire duration of the marriage, how’s that not an intention against procreating? (That’s what counts, not children per se, such as through adoption.)
The marriage is not conditional.
A required part, which is procreation, is conditional. Completeness of the minimum required content of marriage being conditional is the same as the marriage being conditional.
The conditional is only about whether or not they will actively pursue conception.
Not true. It’s not about actively pursuing conception. It’s about stopping to actively avoid any chance of it.
Actively pursuing conception is making sure relations happen on fertile days. Stopping to make sure relations only ever happen on a non-fertile day is a far cry yet from actively seeking conception.
Related: My oldest child got confirmed this year and chose Queen Jadwiga of Poland as her confirmation saint. She had to write a composition about St. Jadwiga, and we all learned a lot of interesting things (which you are no doubt very familiar with, but new to us). For example, Jadwiga got married to a much older man at around 12 years of age, uniting Poland and Lithuania, and had no children until she died of childbirth complications at around 25. So, the question arises, how actively did Jadwiga and her husband pursue pregnancy when she was a physically immature child bride? It’s a very curious fact that there was such a long gap between their marriage and the pregnancy that killed her.
Postponing does not invalidate, except perhaps in extreme situations. Postponing is different from precluding.