The case for sharing someone else's news
The most defensible reason is that something wonderful happened and the other person is too shy to share it or doesn't want to sound like they're bragging. You, as a good friend, want to toot their horn for them. Or, on the flip side, something terrible has happened and they're too overwhelmed to ask for help. Quietly reaching out to their inner circle to organize support isn't gossiping. That's love.
There's also a scenario: What if the news directly affects a third party? If your friend just started dating someone another friend has deep, unresolved feelings for, a gentle heads-up could spare everyone a very awkward dinner party. So, yes, these are all defensible reasons. But sharing any of this news without consent still doesn't necessarily mean you are in the right.
The case for keeping your mouth shut
People hate having their news stolen. Hate it. And sometimes they hate you for it. Social media is basically a graveyard of well-meaning people who couldn't hold it together: the mother-in-law who posted the pregnancy announcement before the parents were ready, the cousin who uploaded wedding photos before the couple could share the professional ones, the grandfather who congratulated the grandkid on the new job on LinkedIn before said grandkid had told his own boss he was quitting.
And then there's the more serious category: outing someone's health condition or mental health struggle before they're ready to share it. That's not just rude — it can cause real, lasting harm. It is 100% never OK to share that kind of information about someone else.
There's also the problem of mutation. By the time your news passes through three people, it's unrecognizable. What started as "Brooke had a medical procedure" becomes "Brooke almost died in surgery." Finally, you might simply be wrong. If you're not right, now someone else has to do damage control on a rumor you started with the best of intentions.
The gray areas
There are also a few other factors that affect how rude this is:
How close you are: Counterintuitively, the closer you are, the more careful you should be. Closeness means they trusted you with something private. Betraying that trust stings more.
Why they haven't shared it: There's a big difference between "she's waiting for the right moment" and "she's scared or ashamed." The second category deserves extra protection. If someone shared something with you that they're still processing — a diagnosis, a pregnancy loss — sitting on it is the minimum of good friendship.
What kind of news it is: Medical issues, mental health, financial struggles — assume these are confidential unless you're explicitly told otherwise. The person shouldn't have to label their own vulnerability with a "do not share" sticker.
The verdict
Sharing someone else's news is rude. Often very rude. It doesn't matter if the news is happy, if your intentions were pure, or if you've been sitting on the information so long, it feels like it should be public by now. It's not your call to decide whether their news is significant enough to protect. If they haven't shared it, that's your answer.