(Still deep in exam time. A five-minute jotting down of thoughts:)
There’s a term in the poly community called ‘compersion’. It means being happy that your partner is happy with someone else, like the opposite of jealousy.
I think, had I queerplatonic relationships, I would comperse VERY easily. To the point of barely caring what my partner got up to. The way I see it, as long as I’m happy in our relationship, it wouldn’t bother me what else they’re doing. If I’m not, it’s probably a fault of our relationship, not other relationships they’re having.
With friends, however, compersion tends to be more difficult.
I think the reason for this- the reason I would find it easier to be in a poly arrangement than a person who started out monogamous, is to do with power. Monogamous people are used to a lot of power. In some cases, enough to say things like “I don’t care if she’s the best receptionist you’ve ever had, I don’t want you employing attractive women!” and have that be seen as reasonable or in some way founded in rationality. Aromantic people have so depressingly little power. Often, not enough to say “It’s great that you’re connecting with her! Now, maybe we could go grab a coffee sometime and talk about it… oh, ok. See you around…” without being unreasonable, irrational.
I think that’s why I’d have an easier time dealing with jealousy than previously monogamous people. I’m so used to having no power at all, to the idea that, throughout my life, I might only get a tiny handful of relationships where my wants are respected enough to keep me on as a friend in some vague capacity after pair-bonding, that the idea of any power at all, any statement of “You’re special to me. Don’t leave,” any hint that I’m worth basic respect, that my love is worth prizing, would mean the world to me. As an aromantic person, that basic level of satisfaction, that major poverty of power, would be a state beyond a dream.