These people need to do whatever it takes to protect themselves, so how their friends feel because they haven't told them the truth shouldn't really come into this. Sharing secrets shouldn't be transactional anyway.

Yes, it's painful to pretend something that isn't so, but we have no idea how much more painful it might be for them to have friends who want to discuss it.

It's a form of grief and grief is exhausting. Theirs isn't going away because they will presumably never have the child they long for.