It's probably the job combined with this major unheaval of a new man and the intensity. I know plenty of men in their 40s and even 50s that went on to have second families after believing that they were done.
My ex and I, he was 40 when our oldest was born, for example. One of his nephews was 43/44 when his 5th child, 1st with his new girlfriend came along, post separation/divorce.
Unless it's a deadset no, face to face, then there's probably one of those chances of 'let's see where this goes' moments.