Fair enough, but I'd say there also seems to be some sort of perception that I'm under some sort of moral obligation to people outside of my marriage to be their "secret keeper" or confidant.
I'm not and I simply make that clear. In the few times over the last couple of decades a conversation has started with "Please don't tell your husband this but ..... "
I simply stop them. I'm not a Priest. I'm not a Therapist. As I said before, if it is something they don't want my husband to hear, I make no promises to that and they need to choose somebody else to unload on.
If that works for you, thats great and I'm sure your friends are thankful that you forewarn them that if they choose to share something with you, you may tell your husband.
I don't look at myself as a priest or a therapist, I see myself as a friend and yes I do feel I have a moral obligation to my friends. When I married my dh, I didn't agree to give up my confidant to them status, the relationship I have with them doesn't change just because I'm now married.
