I think that she is unhappy, maybe its something that she cant quite put her finger on, maybe its her weight and shes too embarrassed to come out and say that, maybe its something else that she just cant bring herself to talk about. Who knows.
Does that mean that its legitimate, probably, does it mean that its your fault? Absolutely not. Shes your wife, and its your job to help her through these things. BUT... if she cant, or wont give you what you need to do that, well, there isnt a whole lot that you can do.
I dont think that this is about you... I think that it is 100% about her. Your just the focus of her bad vibes. Where does that leave you? Im not sure. But I think that you should stand up for yourself.
I guess I gave the wrong finger to the wrong man...