According to the on-line Indiana marriages webpage, Frances (Fanny) ALEXANDER m. Calvin S. WINEINGER in Jackson County, Indiana on 14 Mar 1840.
In all probability, James ALEXANDER had already died by that time. . . . other possibilities (I suppose) would be divorce oroutright desertion. But death is much more likely. I wonder if there would be a gravestone for him in the same cemetery whereshe was buried.
Do you have a complete list of Fanny and Calvin's children?
I know of no children of James & Fanny. Were there any Alexander children (under 14 years of age) enumerated with Fanny & Calvin in the 1850 census? I've not looked since I hadn't realized that she had re-married.