About a month ago, my best friend brought over his new partner. I'd already met his other partner of several years, but he started seeing an additional person, and brought her to a party a friend was throwing. We immediately hit it off, lots of flirting and what not, and she asked for my number. Lots of talking and flirting, and then we decided to hang out and spend the night together. It was a lot of fun, and I'm interested in furthering things, but I'm not sure how with respect to everyone? Should I just ask her out? Should I sit them both down and talk about it? Should I wait to be invited? I'm not sure, but I want to make sure I do it in such a way that works for everyone and doesn't violate any bounds. Please let me know what you think. I believe I'd do okay in such a relationship, not getting jealous and giving everyone their space to participate in the activities they want, I'm just not sure how to start it.
I'm a little confused as to what you are hoping for here. You describe this as "joining a poly relationship" and suggest the possibility of being "invited" but it is not clear to me whether you are interested in being in a relationship with both your best friend and his partner, or whether you are interested in just being with your friend's partner.
From what you have said, it doesn't sound like there is romantic interest between you and your best friend -- or if there is, it hasn't been discussed previously? So I am going to assume that you are only romantically/sexually interested in the partner of your best friend. (Feel free to correct me if I am wrong.)
If that is the case, then there is no need to join both of them in a relationship or to sit down both of them together, or to wait to be invited into their relationship. Your interest is just with her and so you can talk to her about it directly.
However, it should be said that dating your best friend's girlfriend might be fraught with unexpected challenges. What happens if she breaks up with one of you? Will there be hurt feelings and tension between you and your best friend if she continues with one of you but not the other? What if your friend doesn't feel comfortable with his best friend also being a metamour? What about possible tension/discomfort when the three of you are together? Will one of you start to feel insecure or envious of the other?
There's just a lot to process when you have a strong friendship on the line. The first step is to really think it through, then to talk to each of them individually about what you are interested in and see how they feel. Remember that a friendship is a relationship too -- a relationship worth maintaining. It might not be "worth it" to pursue this romantic connection if there are significant risks to your solid friendship.
I'm confused without names. Let me sum up in my own words with some generic plant names. (I'm happy to go with whatever names you pick if you like something else better. )
You have a best friend. Call him Aspen. He has a partner, call them Birch. Then Aspen started seeing an additional person, call her Camellia.
You and Camellia hit it off and ended up having some kind of hanging out/spend the night date thing. It was fun.
Now you want to continue developing a relationship with Camellia but aren't sure how to join this existing poly network more fully as a potential partner to Camellia.
Is that it?
I'd say talk to Camellia. Tell her you are interested in dating her more. Is she interested in dating you? (Cuz if she's not, no point in going further.)
Or talk to Aspen first since he's your best friend. Because if he's not good with it maybe you don't bother to tell Camellia anything and you do not pursue a relationship with her.
Whichever you approach first? Say you want to be respectful to everyone so want to invite both to coffee and talk things out more fully. Make sure everyone is on the same page before starting anything.
Because she might not want to further things. Or they may have agreements about her not dating his close friends because that's too weird. Just as her dating his parents might be too weird.
You have to learn what it is you are getting into and if they have agreements that could affect you so you aren't going in blind. And they have to learn the things you value/want and how you would want to be treated and what your limits are. That's fair.
I want to make sure I do it in such a way that works for everyone and doesn't violate any bounds.
Sorry for any confusion as to what I mean! I'm not poly, so I apologize for not knowing the proper way to address things.
First off, I love the idea of using plant names, that's super cute and I'm totally stealing it. But yes, that's exactly it. I think maybe I'll talk to Camellia first, see if she wants to further anything, and then we can both talk to Aspen? That might be a good idea.
Camellia said the three of us would do something together at some point, so maybe I can approach her before then and we could talk about it, figure out what we want and all that.
I think being honest and up front and asking for a time to talk would honor this want. That is fair to you and to everyone else.
It sounds like you have the right idea, talk to Camellia first, then if she is interested, follow up with her and Aspen both. Keep us posted if you're willing and if you need further advice.