Ammi:
Yep, so St Augustine did not see the clause as referring to invalidity. He saw it as grounds for civil divorce/Church separation and still binding.
Umm… I’d disagree with your take-away. If the question is "on what grounds is divorce permissible?’, Augustine agrees with Christ and the Church:
none. If the question is otherwise – which seems to be the direction that you’re now twisting the discussion – then a different question (“is invalidity a valid cause for divorce?”) leads to a different answer, which is already provided by the Church:
yes, an invalid marriage is not binding unto death.
This is what St Augustine explained the exception meant. Divorce, with the bond remaining.
No, although I appreciate that you wish this to be the case. If it were “divorce”, then re-marriage would be valid. Augustine – and other ECFs – agree that subsequent re-marriage is invalid. Therefore… “no” – they’re not talking about divorce.
Here is some more evidence of the exception clause referring to adultery justifying separation without remarriage, and NOT referring to an invalid marriage.
Umm… you realize that the very opening paragraph you cite, actually supports our contention and refutes yours… right?