I think a significant element of my aversion to the idea of monogamy in general is that I don’t want to have to be afraid of getting close to other people I’m attracted to. It seems like in many ways the purpose of monogamous arrangements is to preserve the sense of intimacy and specialness of the relationship, and that means being careful not to let other relationships with people you’re attracted to become similarly special or intimate. That idea makes me incredibly uncomfortable.
I’ve written a little bit about this before in the context of talking about hierarchical relationship structures and which types make me comfortable or uncomfortable. It’s that discomfort with putting an arbitrary cap on the level of closeness permitted with one person vs. another. I can’t make that palatable. It’s possible it’s a kind of thing that could just happen naturally (i.e. you just become less likely to develop that same type of closeness with more people once your drive to find it is satisfied by the relationship(s) you’re already in), and I have no issue with that, and I certainly have no objection to avoiding getting into large numbers of relationships in order to make sure I have enough energy for the ones I’m already in. Frankly, though, I would expect that variety of self-limitation (the conserving your emotional energy/resources variety) to come relatively naturally to me, because I care about the relationships I’m in, and I already consciously act to preserve them.
Preserving energy for relationships is one thing. Preserving an intangible sense of specialness by disallowing emotional intimacy with other people is another.