Rationale is to explain away loved-ones behavior changes. ( I would think close family would be first; Second would be extended family, and third would be close friends who are part of the extended family? I opine that a general announcement like marriage bans or really good news would be inappropriate, as it would also notify the evil scum that looks like good news for them!!
One thing I have learned about this disease is that everyone who has it progresses differently, some faster, some slower and in every different way.