i guess you are right
i should clarify that those i have in mind are not necessarily blabber mouth, they are just very close with their spouse children or/and grandchildren
but still
I started to add a comment about that but it could get very long.
It depends on the confidence. If it has no bearing whatsoever to the spouse it would be commonly accepted by most to be willing to share it and not feel they had broken a confidence, because a lot of people need a sounding board.
Some people can't hold in news and must share, so sharing it with someone "safe" like that may be like a form of indulging gossiping tendencies, but hopefully they've evaluated it not to damage the confidence.
Of course if the spouse (or grandchildren or whoever) are intimate with the situation, sharing could be completely a breach of trust.
Different people have different reasons for "needing" to share, different ability to keep a confidence completely, and different abilities to keep things safe.
It becomes complex to discuss in theory only.
But basically we need to evaluate people for that, evaluate the need for the confidence to be kept, maybe explicitly say it shouldn't be shared, and with all of that, do our best.
But someone could have had innocent motives in sharing, if that's what happened.