And although their life is basically over, they've raised their family, etc. how much you want to bet ONE or BOTH of them "just so happen to" get remarried. EVEN THOUGH they are beyond childbearing years ...

You win the prize.  Yes, they BOTH "remarried" fairly quickly after the "annulment".  LOL, one of them, the man, went to an Eastern Rite church and the priest was telling them what they had to say, and one of the things both of the couple had to say was, "I never never been married before to someone else who is still living."  And the priest nodded for him to repeat it when even the "groom" was confused about how to answer.    Both of them deep down, despite their denials, know full well that the one they're with right now is not their spouse and that they're living in sin.  Hopefully they repent before they die.

Well, presumably they NOW understand what marriage TRULY is (vs. before), since to make the judgment that they didn't know what it was before assumes that you know what it is that you didn't know, i.e. the true nature of marriage.

And although their life is basically over, they've raised their family, etc. how much you want to bet ONE or BOTH of them "just so happen to" get remarried. EVEN THOUGH they are beyond childbearing years, they screwed it up SO BAD they were living in sin for 25 years, and even though they have children (talk about baggage!) and were used to a single man/woman all that time -- an individual who is A) still alive and B) almost certainly going to be actively in the childrens' life going forward.

There are plenty of *widows* that say "I'm done" and don't even try to get remarried. I realize it's lawful to get married when your spouse dies, and plenty go that route. I'm not criticizing those who do. But I can certainly understand the argument, "I've been there done that. I'm not 21 anymore. I have my children. I'm not going to complicate my life by getting married again."

That's what my Mom did when she became a widow at 54. She's 71 now, and never so much as courted anyone since my dad passed away. I don't believe she's the first widow to do this.

A lot of women do fine after they become a widow, specially if they are over 50 or so. Men usually don't. Even when they are over 60 or even 70, they will find another woman, usually to ruin the remainder of their life.

Just the other day I met a man whose wife died of cancer a few years ago. He is probably around 60. He is now living (not married) with another woman. She gave me the impression of being very bossy and feminist. I bet that she is a divorcee. Terrible decision, in my opinion, even if he had married with her and adultery was not an issue.

THIS^^^.

If you run into ANY ex-Catholic (and they're usually the most vitriolic anti-Catholics out there), if you scratch just a little bit below the surface, it's always due to some sin they fell into and want to keep falling into and condoning.  Every.  Single.  Time.  Just like with Luther and Henry VIII, both of whom did not actually leave for "principles" of theology or doctrine, but due to moral reasons, and then only after that saw the "light" about the "bad doctrine" of the Church ... as an after-the-fact justification for and rationalization of their heresy.

I would have to say very often, but not every single time, no! 
I personally know of someone who lost the faith because of "intellectual" reasons, read books of Richard Dawkins... Lives a perfectly moral life, but of course does not attend Sunday Mass. Is more charitable than a lot of Catholics I know, too. No sin they fell into, just read the wrong books, even though I know that's a sin in itself ;-)

The vast majority of annulments post-Vatican II are given for reasons of "defective consent". Before Vatican II, I think other reasons (rarer today), like not believing matrimony is a sacrament or there being impediments discovered after marriage, made up a higher percentage of the annulment cases.

I'm not sure how the Church currently handles these things.

But according to St. Thomas Aquinas, if the parties to the "marriage" were truly ignorant of an actual impediment to the marriage and an annulment was granted after children were born, then the children would be legitimate in the eyes of the Church.

However, if the parties to the "marriage" were aware of the impediment and proceed with the simulated "marriage" anyway, then the children would be illegitimate in the eyes of the Church.

See Aquinas's discussion of this topic here:
https://aquinas.cc/la/en/~ST.IIISup.Q68.A1

Thanks for the information.  I did not realize that legitimization of children of a putative marriage went all the way back to Aquinas.