I was a Catholic from birth to 40+ years. It was a mortal sin to eat meat on Friday (until the change in the ‘60’s) or during lent, or to not fast on certain days (Ash Wednesday, Good Friday). You are absolutely correct that there should be a willing heart, but most Catholics do it out of the fear that they will go to Purgatory (or worse) if they don’t “follow the rules.” My parents still don’t know that they are assured Salvation. Christ died for us to be free from constant worry of whether or not we have done enough good works.
Do you think a person ever intended grave evil by eating meat on a day of abstinence? I, personally, would doubt it, unless it was somebody intending deliberate disrespect to Our Lord (for instance, aggressive atheists sponsoring a public pig BBQ in fron to St. Patrick's on Good Friday: which is exactly the kind of thing the militant homosexual group Act-Up has done, by the way.)
Some people may have a mistakenly over-scrupulous conscience about such things as an ill-timed burger, and for them I feel sorry. But I would hasten to reassure them that salvation depends on our opening our hearts to the goodness of our Good Lord Jesus; and He gives, not fear, but peace.
Amen? Amen!
God bless you and your family, Deb!