Polyamory, Aromanticism and Orientation
One question is whether polyamory is a lifestyle choice, an orientation, or a mix of both. Personally, I do think that there's an orientational aspect to polyamory. There are some people who seem naturally inclined to polyamory - including some who find themselves cheating because they couldn't admit their desires to their partner. There are others, meanwhile, who probably can't feel satisfied unless their relationship is monogamous - and not necessarily because they're insecure.
After all, the urge to pair bond is something that is biologically programmed into certain species (there's some really interesting research going on into prairie voles and their pair bonds), so it stands to reason that humans might be programmed the same way.
And of course there are people who seem happy with either monogamous or polyamorous relationships, but maybe they're just the poly equivalent of biromantic people, people who are naturally flexible in that dimension.
But once thing that I've been speculating about is whether this dimension applies to aromantic people. After all, there are other dimensions of orientation that simply don't apply if you're aro or ace - you can't be both asexual and heterosexual, for example. (Though you can be grey-ace and heterosexual.)
But on the other hand, I've seen a lot of aros who certainly look quite poly. This person is an example. They describe a rarely sexual long-distance platonic partnership with a married woman and another platonic partnership with a a person they see on a regular basis. And they're open to more platonic bonds like that.
Which makes me think that the desire for strong platonic bonds also contains a poly/mono dimension, and me? I'm a lot more towards the mono end (if I don't count my brother).
Thinking back, I've only ever had one best friend at a time, even as a child. Even when I had other friends, none were as important as the one friend. I have also sometimes felt like other friends were 'intruding' when they sought more closeness with me and my best friend, even though I don't show this reaction for fear of hurting my best friend and often the lesser friend as well, and possibly driving them both away. It's like there's one space in my heart for "best friend" or "QPP" or whatever, and when it's full, no other friend can get that close.
So I think you can definitely be both aromantic and polyamorous. And personally, I'm probably aromantic and monoamorous.