What are your expectations of privacy when confiding in a friend who has a significant other?

Part 1:

Do you expect total privacy or do you just accept that your friend will share your confessions with their SO even if you ask them to not say anything to anyone? Do you even bother asking them to not share with their SO?

Part 2:

Conversely, for the jellies in relationships: when a friend confides in you, do you share it with your SO or do you respect your friend’s right to privacy? Or does it depend on the severity of the situation? Does the length of the relationship with your SO play a role in this?

Part 3:

Is it unfair/unrealistic to expect someone to keep something from their SO even if it does not have anything to do with their relationship?