I wouldn't put all the responsibility on the more open person. They should be thoughtful and ask before sharing details but the person who doesn't want anything shared should communicate that clearly.
I also don't think it's automatically the more private person whose wishes are the ones respected. It is crucial to find out these things before getting intimate. I have a right to my own boundaries around being open. For example, I have a boundaries that I will not be anybody's dirty little secret and that I will not be closeted (i.e. I may choose to hide the fact that I am queer, but nobody else has that choice though I may take other's feelings into consideration). That means that if I am intimate with somebody, that fact is mine to share if I wish. I certainly want to be sensitive to the other person's wishes for privacy, but if I am told after the fact that they want nobody to know, that is too late. If I am told in advance, then we can see if it is a good idea for us to go there at all.
Living with my partner Mya
and metamour Hank. Seeing Lily.