GE: If you want to have an open relationship and talk to your partner about it, I think there are a couple of foundational things that need to be discussed first, which is that firstly, that you can't really have an open relationship as a way to make your relationship better, like if you're in a relationship that's rocky or there's been infidelity or anything like that. Basically, if the relationship isn't super solid, you can't open the relationship — it will almost always lead to a breakup.
Also, both people have to be completely down for it. One person wanting to open the relationship and the other person not wanting to open the relationship is a recipe for disaster. So when it comes to bringing it up, I would always recommend having an outside person to facilitate this, like a couples therapist or sex therapist or a sex coach who can help explain this and help you and your partner negotiate some of the boundaries. Because if you've never done this before, it can be very it's a very vulnerable time, and it can be very scary because, for somebody who hasn't thought of this before, the partner who they're having this information brought to them, it can be very jarring. But usually, in a really good, open dynamic, both people have talked about it and are interested in it — for instance, talking about threesome fantasies, or talking about maybe even having a threesome. A threesome is actually a great place to start with open relationships because both primary partners are involved and you can kind of see how the dynamic works. And that's definitely where I would start: discussing the possibility of having a third person in your sex life together. Then you guys can negotiate that together.