bpt — I’m sure there are people who have kids due to “peer pressure” — but there are also plenty of people who want children. Why do you assume the reason your “Couple B” is having treatments is due to pressure?
And since infertility, both primary and secondary, are often medical conditions, it is normal for someone to feel “something is wrong”. This is not a discussion on people choosing a smaller vs. larger family — it is about someone facing circumstances beyond their control that prevent them from having the family they were hoping for.
Beyond that, I don’t understand why “secondary infertility” is something you dismiss in such a belittling fashion. The concept that someone cannot feel like they are “struggling” just because others have it worse seems a bit bizarre to me. Would you say that someone who is struggling with Parnassah in a low paying job has no right to feel bad because there are so many people without any jobs at all? That someone with an illness that has a good prognosis cannot feel pained because there are people with terminal illnesses out there? Everyone has their own nisayon, and I believe that belittling someone else’s pain is insensitive no matter who you ask, even if you think they have no right to feel it.
I have a relative who has been trying for over 8 years to have a third child. Of course she appreciates the bracha that she has of her 2 great kids. She and her husband are wonderful parents, and really wanted a large family. Her pain of loosing that dream is certainly not the same pain as a childless couple, but it is very real nonetheless.