Reply To: I'm gonna marry a feminist yekke girl

PBA – Haven’t seen it in a while, and don’t own a copy, but I distinctly recall seeing 3 in R’ Yerucham. If I remember correctly it’s in issur v’heter (39 or thereabouts). The Maharil is in Minhagim (issur v’heter, 5 d”h ochal, and 40, 4). The Mabit is (I think) in Sh’ut discussing waiting between milchig and fleishig (as oppose to visa versa). Waiting 3 hours is also mentioned in Chayei Odom Siman 127.