I've indexed a marriage announcement for a Conrad Friedrichs & Dorothea Sagert, m. 22 Aug 1846, from one of the local German newspapers. Given the complexity of some German families' naming customs, spelling variations in early records, and the reality that some immigrants with young children married after arriving in the US, this might be your couple.
"Milwaukee's German Newspapers; an index of death notices and related items" (1844-1950).
Gary Rebholz, compiler/editor
Indexing Milwaukee's German newspapers continuously since 2007 ... because _somebody_ had to.