...do you tell your SO? What if they specifically ask you not to tell your SO?

I always assumed that everyone kept confidences from their SO! But over the years I learned that if you confide in someone, most everyone expects that the person will tell their SO. Unless you specifically ask for someone not to mention it to their SO.

I don't say anything either way, unless somehow a secret would impact the health and safety of my SO... which hasn't ever happened so far!

If a friend asks you to keep a secret, do you tell your SO? What if they specifically ask you not to tell your SO?