ooo, such interesting conversations going on - this is exactly what i was hoping this thread would become. thanks everyone :-)
So, some thoughts... @HollySass - i think the reason why there are words, is because there are things which exist which don't really have words otherwise. saying 'my partner's partner' all the time is a bit clunky. Why not invent a word for it? but, on the flipside...people who are poly are, in my experience, often quite nerdy about relationships. there is also quite the overlap with board gaming and D&D, though that's not really my thing. Also, whether you are poly or not...I don't think it really matters. As i said upthread, there are some people who are very specific about what 'counts' as poly or not, and it can be useful to agree definitions so people know what they are getting (for example, there are lots of poly people who aren't interested at all in casual sex). For me, in general, i think just a broader freedom to engage in non-monogamous relationships however we want to define them would be great. I really enjoyed reading The Ethical Slut on this :-)
On @TackyJewellery's question around who you are attracted to. I think @ComtesseDeSpair's answer is definitely true - if you're not looking for a 'one and only', the avenues open slightly. but i also think different people ahve different ways of experiencing sexual attraction. a former partner of mine enjoys sex almost like a hobby - he is just open to experiencing new things with new people, if they are open to it, and only that basis is often attracted to a really wide range of people. for me, it's a bit narrower...i can have a ONS on a fairly shallow basis, but i get a lot more satisfaction out of longer term connections and attraction is very much about getting to know someone a bit. I find it hard to be attracted to someone on a greater level than 'oh, yes, they are objectively good looking, fancy that', without getting to know them a bit and finding their personality attractive too. My long term partner is even more specific than me, and doesn't find people he's attracted to very frequently at all. but when he does, he tends to fall quite hard, and it's super cute to watch.
This summer, i did go out specifically seeking people. for me, I had been looking forward to being a little hedonistic when i split up with my long term mono relationship, and because i kind of ended up falling in love with two people, i didn't do it really - because i figured trying to handle two relationships and learning how to be poly was enough of a hassle. then the pandemic happened. so i felt like i hadn't really explored this side of me. and when Ted and I split up at the beginning of the summer, it felt like a good time to explore it. I didn't really intend to start other 'serious' relationships, but it turns out that that is kind of the way my brain works. I just sort of make strong connections with people.
i'm not looking now, and I think if i met someone I really connected with, i would have to think very carefully about what I wanted to do - because I don't really feel like i have the space for anyone else in my life at the moment. As someone said to me once, despite having the freedom to say 'yes', a lot of polyamory is about saying 'no', just as much as monogamy is.
In terms of that 'drive' to look elsewhere...i think this is an interesting question. different people approach this differently. some people really want to experience many different kinds of relationships - and sometimes these people can be a little toxic. i've seen them called 'collectors'. others don't necessarily want a 'serious' relationship, which is fine if they are upfront from my perspective.
other people dont' have a 'primary' partner. Craig and i are, i guess, descriptively hierarchical, in the sense that we've been together for a few years now and are quite central in each other's lives, but i wouldn't call it a primary relationship in that it takes precedence over others. it's not something that is being preserves, or protected, against other relationships, int he way that some forms of ENM/poly work.
for me, it's about how i see and understand life and relationships. I have a bit of a blurry understanding about romantic relationships - i'm not a super fan of strictly defined categories, and i also don't see why i should prioritise romantic relationships over very long term friendships. so for me, it's about individual connections and being able to act on them if i want to. if i meet a new friend, i don't not-explore that connection because i already have friends. similarly, if i'm attracted to someone, i might want to pursue that. but i think it's a very different way of approach life and relationships in general, that wouldnt' appeal to a lot of other people. and that's ok :-)