I was under the impression that a marriage was invalid if the couple didn’t understand that marriage is for life, is exclusive sexually, and is open to life - at the moment of marriage. E.g. Cheating wouldn’t invalidate a marriage, but going in thinking you can cheat still would. The same would be true with divorce. Getting divorced wouldn’t invalidate a marriage, but at the moment of marriage thinking you can always divorce and remarry would. This would be because the couple isn’t really consenting to marriage if they dont understand what marriage is. Perhaps, I’m wrong?