"Just reasons" are spoken of quite often in NFP classes.
I taught NFP for 10 years, and I know that grave reasons were thoroughly discussed in the classes I taught.
However, multiple members of the Catholic Caucus here, not just trads, have related hearing NFP presentations at Pre Cana classes where no mention whatsoever was made of "just reasons." Furthermore, I know that locally, since our bishop gutted the NFP office and we had to go independant, the NFP courses officially offered by this diocese were at times taught by instructors trained by Planned Parenthood, and that no mention whatsoever of Catholic morality was made in these classes.
Furthermore, I seem to recall Catholic FReepers relating taking NFP instruction in which NFP was taught with no reference to "just reasons."
So, given my personal experience as an NFP instructor who has seen values free NFP taught in his own diocese, and judging by the stories of others, I must correct you. These are indeed occasions where little or no mention of that other part of the Church's teaching which insists that couples need "just reasons" are made in the context of NFP presentations and instruction.
I know that locally, since our bishop gutted the NFP office and we had to go independant, the NFP courses officially offered by this diocese were at times taught by instructors trained by Planned Parenthood,
Oh my!
However, multiple members of the Catholic Caucus here, not just trads, have related hearing NFP presentations at Pre Cana classes where no mention whatsoever was made of "just reasons."
Pre Cana is not the place to learn about NFP. While it doesn't take much more effort to mention the just reasons, it comes as no surprise that it is not during this event.