HomeschoolDad:
Some say nowadays that NFP may be used at will, and that no reasons need be considered. I would welcome a papal or magisterial clarification of this. It is hard to understand how at one time a reason (grave, serious, whatever adjective you want to use) had to be considered, but now the couple doesn’t have to have a reason. Some say that the mere fact of using NFP rather than ABC is proof of a couple’s bona fides. This, too, is hard to understand. NFP should be used in dialogue with one’s confessor or spiritual director.
I would say that any couple who is using NFP has a reason, and most likely a good one. NFP is a sacrifice, and not one that most couples wish to embrace. It requires ongoing, regular discernment and communication about their reasons for using NFP. Just because they don’t choose to make their reasons public doesn’t mean they don’t exist.
Only the couple themselves are in a position to discern whether NFP is the best course of action. The bar for “serious reasons” isn’t that high. In the link that you provided, Pope Pius lists four categories: medical, eugenic, economic and social. Those are pretty broad categories and can include reasons such as the age of the husband or wife, serial miscarriages, debt, poverty, depression, other children with special needs, being overwhelmed, being without social support, etc. Only the couple themselves can determine whether the reasons are serious enough
in their particular situation, to make the sacrifices that NFP entails and we have to trust that a couple who has made recourse to NFP has discerned this for their situation.
Sure, a confessor or spiritual director can be consulted, but it is not necessary. I did actually have this conversation with my confessor at one point. He gave me his opinion that NFP was fine for the circumstances I was facing. I appreciated his guidance and discussed it with my husband. We ultimately decided not to use NFP and that was fine, as well.