Question:
Answer:
Not at all. Couples are free to have as many or as few children as they choose based on their circumstances and their relationship. Obviously, it would be a very good thing if couples were as generous as possible in having children. Yet this generosity has to be measured according to their capabilities and relationship. There are many people who feel that having a very large family without an extended family nearby is too difficult a task, and so they tend to have fewer children.
The point is clear: we are never allowed to use immoral means either to avoid conception or to foster it; rather, we should strive to give our children the best possible upbringing, materially, spiritually, and educationally. There is no way that the use of NFP, even if the couple is not being as generous as they could be, amounts to a grave sin, because the marriage acts undertaken while using it are perfectly moral.