I found it puzzling too, that for a long time she did not disclose that it was her 2nd marriage, and that her oldest son, is her child from that 1st marriage.
But she explained that it was to protect her oldest child.
She felt to disclose that her marriage to Dan was a 2nd marriage, that that disclosure would also cause her eldest son's privacy to be lost.
As her eldest son got older, she discussed this with him, and eventually he told her he was comfortable with her disclosing this, and that it was all right for her to tell the full story. And so then she did.
As to why she decided to choose not to restore her marriage the 2nd time...
if indeed Dan really did want to restore the marriage again -- which isn't clear BTW...
and as he has remarried, to his HS sweetheart no less...it is now a moot point. They broke up 2 marriages to be together...a much too common story.
What she's said, is that b/c she wasn't pursuing a restoration -- that caused Dan to start pursuing her again. Which is very DB!
What I gather from what she's said, it is b/c she truly decided that she was happier living in singleness, with God as her husband.
And I do understand and respect that decision.
It is certainly a biblical option to choose to remain in singleness.