Was Robb Stark's wife or her mother complicit in the "red wedding"?

In the book now, not the HBO series. Robb's mother complains to Robb's wife that she's not pregnant and the wife says she's trying. Then Lord Tywin Lanister, who has helped plan the red wedding, says with all certainty, "Robb's wife will bear him no children." In the book the wife does not attend the red wedding and AFAIK she was a Lady from a family who Robb defeats. There was something about her mother being a little sly or secretive.

Did anyone come across any information about what became of the wife and what her reaction to the red wedding was, or what the mother was up to?