I believe I said as much in my replies on the issue.
Also from RobbieS on post #1681, IMRight again on P-1690 and P-1703, read them and see how in agreement you Catholics are.
If you and a few Christian friends (say your whole church) agreed to observe two days of prayer and fasting (say over the financing of a new church building) and you later decided that you were a tad hungry so you had a cheeseburger... would you not believe that you had sinned?
I thought that made the point that: yes, eating meat on a Friday in Lent IS sinful for a Catholic but no, you don't go to Hell for doing it. Perhaps I should have been more explicit.
Certainly the Church has the authority to order a fast of it's members. And for centuries, we as a body have fasted together during the time of Lent (with variations as has been posted by others) and at certain other times. This is a sacrifice we make as Catholics in rememberance of far greater sacrifices made on our behalf.
My point (poorly made if your response is any indication) is that your wife's understanding was somewhat... unrefined. Catholics recognize that they have fallen short of the ideal (sinned) by not living up to the sacrifice we corporately choose to make.