You're partner decides who you can or can't date? I thought the idea was to have "relationships" outside of the primary relationship (that didn't have anything to do with your partner and that relationship). Interesting...
Yes, that is usually one of the golden rules of a poly relationship. Your secondary relationships are not secret, usually the primary wants to meet them and approve of them first. If the primary objects for any reason then they don't see them, or it is considered cheating. While the relationship does not involve the other partners, it does not mean that you can do anything you want.
Swingers on the other hand often allow for non-permision based play. But they typically aren't entering into relationships with any of the people they go out with.