In the article it's unclear if this man planned to have either of his first two children. His first wife became pregnant soom after the marriage, then 'disaster' struck and his mistress become pregnant. I don't get the impression he planned for either child.
Now of course he should have been mature enough to take precautions. But perhaps he did. Perhaps the women told him they were on the pill and he trusted them. Then for whatever reason, the contraception failed. Perhaps one or both of those women wanted babies at all costs.
You can heap blame on him for not being a good father, but he might have been quite blameless in choosing to have those children. He might have made it clear to his wife and mistress he wanted no children. Fate or design overrode him. He wouldn't be the first man in his twenties to be avidly anti fatherhood. Yes, he should have made the best of it and supported his wife and later his mistress. There's no knowing if these women (presumably in their twenties too) really wanted to be a parent at that age, either.
He says in his thirties, he met his third wife, and she already had a daughter. He chose to have a family and it worked out.
For me this article is a very annoying one because I don't know all the facts. There are too many questions left hanging and IMO it's open to interpretation.