Is anything else about her behavior "off?" Does she openly flirt with him or anything? It could be that this woman sees that your husband is a stand-up guy amd that you have a solid relationship, and is one of those insecure women who are just trying to see if their situation at home is normal or not. Do you feel comfortable asking her why she is asking you personal questions? Maybe you could ask her if everything is okay at home and approach her that way. It'll give her space to open up to you, and if her intentions are anything else, it gives you an opportunity to set a boundary with something like, "We dont like discussing our relationship casually. If youre having trouble, we dont mind offering our opinion, but otherwise we would prefer to stick to other subjects."