I’ve heard of a few convert Catholic priests who can have relations with their wives until she dies, but then can’t remarry. Does anyone know if Cornelius is taking a vow or a promise or is this something he can voluntarily go back on with no sin involved?
Married Catholic clergy do not take a vow or make a promise to be continent. We make a promise of conditional celibacy in that if our wives pre-decease us then we must remain celibate and cannot remarry.
If Deacon Cornelius is making a promise to be continent after ordination, then that is entirely of his own initiative - and all the more praiseworthy because of it. He would have to have his wife’s agreement in this, of course.
If they subsequently decided that they could not live continently, he would not be breaking any of the Church’s laws, therefore, it would be no more sinful than breaking any other promise. However, the prospect of breaking a promise we make to God should make any of us pause before making such promises without due care and consideration.