Who ever claimed that not eating meat on Friday was some kind of doctrine? It was a charitable (& perhaps political) decision (I think during the 17th century) by the church to aid fishmongers who were starving because nobody was eating fish. It was intended as a sacrifice of the people called by the church. We continue it today as a guidline for sacrifice during the season of lent (along with other sacrifices) in rememberance of Christ's 40 days in the desert and in preparation for Good Friday-Easter.
Nobody ever claimed that Scripture requires us to not eat meat.
I'm sure there are other x-catholics who had the same understanding my wife had, it was a sin, and had to be be confessed to the priest if they ate meat on any Friday.