I don’t know why you’ve taken such an angry tone (my "oh-so-delicate conscience???), but to answer your question-
The problem arises when the civil definition of marriage no longer resembles the Catholic definition of marriage such that the two concepts are contradictory. The Church teaches that valid marriage requires 3 conditions- proper form, proper matter, and proper ministers. The form and matter of the sacrament of marriage are the free consent of the individuals to be married, the proper ministers of the Sacrament, according to Canon Law, are the man and the woman to be married, and the proper minister of the Rite is the local ordinary.
There are provisions in Canon Law which recognize valid marriage of non-catholics and even non-baptised Christians, so long as they have the proper matter, form, and ministers- meaning civil marriages are recognized in the Church so long as they are freely consented to, and they are between a man and a woman. The Church does not consider civil marriages to be invalid on the basis of the possibility that civil marriages can end in divorce.
But it would consider them invalid if they were to allow for improper ministers, such as those in homosexual unions. Including homosexual unions in the civil definition of marriage would change the very nature and meaning of all civil marriages.
it would be as though society simply stopped recognizing civil marriage at all, because what they’d be offering would not be marriage as the Church understands it.
Therefore, while society would have something it calls “marriage,” that institution would no longer be compatible with a valid, licit civil marriage according to the conditions laid out in Canon Law.
So. The Church reckons it’s OK for civil governments to allow remarriage after civil divorce without annulment. Betwen baptised Catholics whose previous marriages occurred in Catholic ceremonies and are thus presumptively sacramental.
Which, to use your own words, means in such cases the civil governments are NOT at all offering marriage as the Church understands it! Marriage as the Church understands it is only annullable, and is otherwise, properly speaking dissolved only on the death of one of the parties. The church recognises no such thing under its definition of marriage as dissolution of a
valid and sacramental marriage by divorce, and hence does not recognise remarriage following same. But the state certainly does.
Moving on, and more relevantly to your argument. There are quite a few countries - Canada, the Netherlands and so on, where gay marriage has been legal for years. In those countries Catholics aren’t exempted from the Canon Law provisions regarding the requirement to marry in a civilly-recognised fashion. IF such an exemption were possible under Canon Law, the bishops of those countries would have outright said so, or at least we’d see Catholics in those countries marrying in church-only ceremonies, not legally-binding ones.
I’m angry as you put it (not really so, but I grant it may seem that way) because, unless you’re a priest, bishop or canon lawyer and haven’t told us that you are, you’re very dangerously suggesting that you or any layperson can simply interpret canon law by their own lights. In a manner directly contrary to how the same bishops, priests and canon lawyers, whose job it is and not yours, to determine interpretation and application of Canon Law, CURRENTLY interpret and apply it in jurisdictions where gay marriage is legal.
You’re suggesting that ‘necessity’ in the above canon means whatever you or any other private individual reckons it to mean. It’s doesn’t, any more than any other legal term means what a private individual reckons it to mean.
Again, unless you are a priest, bishop or canon lawyer, seek the opinion of those who are qualified to judge in such matters. Let THEY, whose job and not yours, guide you as to what that canon means and whether it applies as you say.
And don’t confuse the good people here by spouting opinion which you, apparently, have neither the authority nor expertise to offer.