Many of us, in the course of our polyamorous journeys, will have a metamour who we just don't vibe with - who things sit just a little off for us with and we prefer to keep a little more distance rather than maintaining a kitchen table polycule with. If we've been used to close, kitchen table or lap-sitting connections with our metamours it can be disappointing or jarring to realize that we can't make all our network's relationships fit this mold - and the first instance or two of needing to figure out and navigate setting appropriate parallel boundaries (even garden party or relatively close parallel ones) can be challenging. I'd like to talk a little about this situation today.
The first thing to take into consideration is the idea of sharing your expectations and boundaries openly and before you let feeling like you don't want to be buddies (but maybe this meta does) boil into resentment. Part of what makes these conversations potentially tricky is that setting boundaries around interactions can feel like a personal rejection. Especially for those of us who struggle with conflict or tend to people please, the instinct to say "oh it doesn't matter" and "go with the flow" until a higher level of interaction proves repeatedly uncomfortable and truly unsustainable is a strong one. I'd like to advise you that it's easier to set an expectation of less time together (or fewer one-on-one meetings, or otherwise a lower interaction relationship with a metamour) and walk it up very slowly over time and have to pull back just a little when it's too much, than to go along with all of a hinge or meta's suggested activities regardless of our apprehensions and come to a place of resentment about them. If you've hit the point of "I've been trying a very long time and I can't stand it anymore" you will probably need to have a conversation about a more extreme, siloed version of parallel relationships (which will likely have more of the conflict, defensiveness, and pushback you didn't want) than if you just acknowledge, when you first feel it, that you need some space. Being able to share your desire for a more parallel relationship in a way that doesn't say "I find you intolerable" and that isn't rude is often a worry. Remember that you don't need to give a detailed backstory and explanation to express your preference, even (or perhaps especially) if you're making a change to how things are going. A sample script of how you might bring this up with a meta could be:
“Everyone doesn’t get along perfectly with some people, and I think you’re a good person and <hinge> and you seem very happy and well-matched and I wouldn’t want to get in the way of that at all, but I’d be more comfortable if we took a little more space from one another than we have been. What that would look like for me is <strategies & suggestions you've come up with like not hanging out alone, no just the three of you hang outs, timing dates at similar times to you activities, examples below> but still being open to <whole polycule activities together, seeing each other in passing as part of dates with hinge, etc>. This is important to me and I hope you understand.”
With phrasing like this, you're softening the "taking it personal" of the conversation while leaving space for discussion of which of the things you're open to they also are amenable to, acknowledging that a relationship hasn't gone perfectly without placing blame, and reassuring about your respect for their relationship with your shared partner.
The next thing (which many of us might do first) is to consider your and the meta's relative entanglement with the hinge, and based on that, what some reasonable mitigation strategies and boundaries are. If the hinge has some particular expectation of polycule entanglement, you'll need to discuss your feelings with them - and because they care about you even if it takes them a minute to come around they'll recognize that respecting everyone's boundaries is necessary to keep the relationships running smoothly and help you determine how to approach any shared activities. If you recall, boundaries are about the things that are within your control - your actions and reactions -so recognizing how the lay of the emotional land may affect those is important. (For example, a boundary is not "Don't talk to me that way," - that's a request - but it could be "I don't remain in conversations with people who talk to me that way" - your action that you'll leave a conversation if the condition takes place is enforcing your boundary.)
In all cases, if you'd been trying to be more closely connected, like by text messages or by trying to go out for the occasional coffee or drink, removing yourself from group chats and asking the meta to please only contact you by text in case of an emergency is a reasonable way to step back to a parallel place - and having a conversation about what big group events still feel ok is worth doing. Do you think of a monthly D&D group as a small group not a large one? If you're the one who wants the space, you should be the one who leaves the group, in most circumstances. Remember, like we said above, boundaries are about our own actions and not about banning people from things. While there are some situations (like when you cohabit with the hinge) that rules may come into play to help enforce boundaries, generally setting a bunch of hard and fast rules with no room for fluctuation will backfire over time. Talking about specific activities where you're likely to overlap can be a prudent step, but so can dealing with things as they come up, depending on how high or low the frequency of such events is. If you don't share a huge amount of social overlap, or it's all because of the hinge, it's often pretty safe to ask the hinge to be mindful of schedules and not over-planning beyond that.
If you nest with the hinge, the challenge is in setting and enforcing your boundaries while being mindful that you aren't setting your partner and meta up for an implied veto via logistics and rules - take into account whether your shared home is the primary place they can date for one reason or another and whether there are work arounds and mitigations for those concerns. Some examples of changes you might suggest to the hinge & your meta include:
Not communicating with your metamour about the logistics of their being present on a given day a lot; leaving it up to the hinge to plan their dates. Sometimes NPs (especially female-socialized long term nesting partners) have a history of being their partners' "social secretaries" along with their other roles in their lives, and polyamory can be part of how they realize that's what's been going on and back off from that role. Not running your partner's calendar and setting a boundary with a meta that each of you should talk to partner directly to plan is a fairly common transition-from-monogamy boundary that people have to set.
Scheduling dates that they'll be at the shared home when you have plans out of it; if you have another partner who you see outside the house regularly, or a hobby you do every couple of weeks or once a month, that could be an opportunity for them to have "night in" as opposed to "night out" alone time.
If the shared home is big enough (or sounds don't particularly bug you, or throwing on headphones is all you need, because you just don't want to hang out with this meta, not don't want to think about them) just do your own thing and ask not to be invited to participate in (for example) a shared dinner or a board game or a movie, they have their date and you have time to yourself elsewhere in the house. This works best if there are multiple bedrooms so you aren't being turned out of your own space, or you have it to retreat to if partner and meta are using the living room for a movie, for example.
If you have boundaries you want to shift around whether or not sex will be okay with you in the shared home and it was something that was previously established, try to co-create rules around it rather than just handing them down, and try to be reasonable about how they would be enforced - you don't have to agree to anything you aren't comfortable with but keep in mind that if you make an agreement like sex being ok in the shared home if it's when you're out, and you come home hours earlier than expected, it's not the hinge's fault for not mind-reading your early return.
Be polite when you do cross paths with meta in the shared space; being parallel with someone but "in their domain" can feel odd and tiny neutral-to-positive interactions can keep everything feeling less like a personal judgement and more like (which it usually is) just not having emotional bandwidth to make a ton of new emotional connections. (If it helps, think of yourselves as roommates or guests at the same hotel meeting over the buffet breakfast - "Good morning, the weather's nice today, isn't it?" and a smile is a lot nicer than *scowl glower FROWN* and a shove past, but either one will get you both through it.)
If you've passed the point of "really can't handle even seeing them," maybe because of trying to do more contact than you're comfortable with and not expressing it until too late, or being pushed to do more than you wanted - consider setting a trial period for doing so in large or public settings and going from there. They're the most neutral available to you, and trialing it after 6 months can give you a sense of whether and how your emotional state is shifting.
If the metamour nests with the hinge while you do not, most of your choices around suggesting things be more parallel are around shared social time and choosing whether or not you enter the hinge's space.
As above, but in reverse, you can ask to only schedule "nights in" in the hinge's home when meta has a night out planned, whether with friends or partners, and offer your own home or nights out as an alternative date activity at other times.
Figuring out if you're comfortable being in the same space but not interacting with someone can be very trial-and-error - I have had parallel relationships where those ships-in-the-night relationships were comfortable and ones where they were very awkward, and there is no pattern in them that I can discern to advise you with. Be ready and willing to adjust how much time you spend in the hinge's home if it's shared with a partner who you're generally parallel with - because sometimes the "wave hello and disappear" move feels natural and sometimes it feels like a jump scare is about to happen, and if it's the latter that's not super sustainable.
If you're long distance with the hinge and you want to remain parallel with the NP this is harder; as it requires either that the hinge only visits you or that the NP be turned out of their house for a period of time. Offering to help mitigate travel costs that are higher for the hinge now can be a solution to the higher burden of travel now on them because of this change.
Being polite & civil to metamours is the only thing we owe each other, as people in the world. No further relationship is required. If you want to date the hinge in a way that never walks into their home and carefully negotiate public events so that you minimally interact with their NP, go for it. If you think their NP is just fine, but you just don't want to be expected to be their friend independently or go out for drinks or whatever, also, cool, just negotiate it. Most people are relatively reasonable about these things, especially if it's said outright.
If neither of you live with the common partner, logistics largely fall on the hinge - you simply need to have one straightforward conversation with meta letting them know that you'd like to make a change if you have some previously different level of interaction established. It makes it unsurprising and not a "ghost" if you don't carry on as part of group chats or things like that, or if one of you stops going to a karaoke night and 'leaves it' for the other to enjoy with the hinge as a date activity.
If you and this meta are comfortable enough that large groups and occasional social functions are possible but the smaller ones we just talked about are not comfortable, consider negotiating ahead of time whether either or neither of you will attend them as the hinge's date and what kinds of expectations you two have around them. Will deciding who goes home with the hinge ahead of an event ease tension? Does the hinge have a suggestion for how to handle large events where no one is "the date" that is more comfortable for them, like all arriving and leaving separately? Are holidays included in your vision of that, or something that you'll decide closer to that time on an as-needed basis? It's ok to not know ahead of time, but these are the questions that will pop up over the first year or so of being in a parallel polycule.
The transition to a new way of interacting with someone in your relationship network can be challenging, especially if it feels one-sided or like the hinge wants a closer relationship between partners and it's a struggle to set boundaries, but it doesn't have to be complicated. Figure out what logistics make sense for your situation, and if you're comfortable with your meta alone, in small groups, in big groups, or not at all, and have a conversation accordingly. You're all adults and it will work out, maybe with some adjustment as everyone finds their metaphorical footing.