It had happened long enough ago that there was no point in bringing it up, and knowing the Collins family, the marriage was kept out of the history books.
Today's soaps mess-up continuity intentionally -- usually in order to "shoe-horn" some outlandish plot into the already established history of the show
If Barnabas was ten when Jeremiah married her, he would be only 20 in 1795! That seems highly unlikely.
I don't think that when Jeremiah says that Barnabas and him are the same age literally means 'the same age'.
Back then a more established, somewhat "older" man would often marry a very young woman, teenage in fact.
I always thought that Barnabas was supposed to have been around 30. It was very common for men to marry younger women then, although this was sometimes a second marraige after their poor first wife had died in childbirth.
I took a look at Dale Clark's DS Book of Questions and Answers Volume 6 which addresses this issue. Here are some excerpts of what Mr. Clark says: Just because Barnabas was ten when he first saw Laura Stockbridge doesn't necessarily mean that he was ten when she and Jeremiah were married. <snip> Perhaps Laura arrived in Collinsport with her family when she was but a child and grew up with (but not necessarily close to) Barnabas and Jeremiah. Somewhere along the way, as they all grew up, Jeremiah and Laura's paths crossed and they married.
Dale Clark would bother to discuss it in his Book of Q&As? I mean, by bringing it up, doesn't that perpetuate the myth?
It's been awhile since I've watched that scene myself. Is it Laura who says Barnabas was ten, or does Barnabas merely refer to himself as having been just a boy at the time?