My wife and I share 85 cMs of DNA. The likely  MRCA would be someone from Bialystok, where both of our maternal lines resided. I concur with the challenges created by  Ashkenazi endogamy. One of my FTDNA kit reflects more than 30000 "cousin" matches! Unless the match exceeds 175 cMs (and at least a 20 cM longest block] I have never succeeded in connecting the dots to the individual.
Note that GEDMatch has a utility that will "predict" if your parents are "related" .