Okay, here's how I'm understanding your situation: You and your partner are non-monogamous. I am not sure whether you have an open relationship, or if you two are polyamorous (I'm gathering it is open). But your close circle of friends do not know about it. Then there is your partner's good friend (best friend?) who does know about it and has gotten close to you from hanging out together with both you and your partner. You and your partner's friend have acknowledged an attraction to each other, and you want to know if/how you should approach your partner about either having a sexual dalliance with this friend, or starting a relationship with him (not sure if you are looking for something sexual or more of an emotional involvement).
What is the problem, exactly? If you and your partner have been hanging out a lot with this friend, don't you think your partner has observed your attraction to his friend? Is the problem that you think he would be jealous? I don't see why you couldn't bring it up in a lighthearted manner. Don't get all heavy and worried about it. It might even be something he was thinking about. I used to hang out in a large circle of friends and we all dated each other's friends and exes, whatever. If approached in a mature way, it's no biggie. How old are you guys?
Maybe you could give more info to pinpoint the problem for you??? Certainly knowing whether you and your partner are open or poly, and what kind of situation you want to pursue with said friend, would help. If you are poly, what what about other partners? And I'm just curious - are you and your partner married?
Last edited by nycindie; 06-16-2011 at 06:47 PM.