From the other comments you can see quotes from a version of the story showing that there was almost certainly no adultery.
The rest of your conjecture is mostly you applying your own bias to an absence of information. It's a circular argument to use that to support a sense of traditional values.
For all we know the previous relationship was years long and not at all casual. Unless you're going to interpret any non-marriage relationship as 'casual' I don't think you have any evidence in favor of your main point. Especially since this shows a sliver of failed intimacy utterly destroying love and marriage vows. It's not like the man was living a double life, this is something that never came up. To say that their multiple decades of intimacy were not good enough and this shows the true importance of intimacy is nothing more than No True Scotsman.
And I severely doubt that it shows the importance of sexual intercourse either. Just the importance of children, which everyone (to first approximation) agrees with.
Not everyone will agree with my preference for traditional family values, which is fine. Still, I'm not following you:
I'm not getting your answer to the question of why
the sudden knowledge of the child conceived, say, before the marriage, broke up the (long) marriage? My answer is that either (1) evidence of adultery or (2) (as you claim is argued in this thread, no adultery so) lack of open communications, that is, lack of that part of intimate love. To me, answer (2) looks tough to believe. That is, why break up love, home, and marriage over a love child conceived before the marriage, especially given the chance that the man was unaware of the pregnancy? Since you also don't like answer (1), adultery, I'm left without knowing what your explanation is.
My personal preferences aside, if adultery is the only believable answer, then it looks like someone regarded adultery as a really serious problem, enough to break up love, home, and marriage, and, thus, evidence of strong respect for (my) traditional family values.
And, you lost me on a second point: It seems that you are saying that the important glue of a romantic relationship, with marriage or not, is having children and not really just sexual intercourse. In that case, given that the marriage did have children, why use sexual intercourse, with children or not, from adultery or not, as a reason to break up the marriage?
I'll try to be more clear: A traditional view of much of the meaning of sexual intercourse is the implied bonding and, thus, joining of two lives. It's mostly the promise of long term love, bonding, joining, security, etc. that makes sexual intercourse attractive and important. In this way, sexual intercourse becomes important in the marriage, even without children yet or ever. But in part you seem to be saying (1) what is important about sexual intercourse in the marriage is any resulting conceptions yet (2) are saying that loss of love and home, beyond considerations of children, is a tragedy. So, it seems that with (1) you are saying that sexual intercourse without children is not very important but with (2) you are saying that loss of that part of love is important. You seem to be saying that Bob and Martha can have a great marriage with three great children, still are swingers and have semi-public sexual intercourse with a crowd of strangers or casual friends, yet break up their marriage once there is knowledge of a love child conceived before the marriage. I can understand traditional values and even swingers, but I can't understand how such parts of those two can be combined in one marriage.
The rest of your conjecture is mostly you applying your own bias to an absence of information. It's a circular argument to use that to support a sense of traditional values.
For all we know the previous relationship was years long and not at all casual. Unless you're going to interpret any non-marriage relationship as 'casual' I don't think you have any evidence in favor of your main point. Especially since this shows a sliver of failed intimacy utterly destroying love and marriage vows. It's not like the man was living a double life, this is something that never came up. To say that their multiple decades of intimacy were not good enough and this shows the true importance of intimacy is nothing more than No True Scotsman.
And I severely doubt that it shows the importance of sexual intercourse either. Just the importance of children, which everyone (to first approximation) agrees with.