I was talking with Topaz and spoke/realized something at the same time. I don't believe there are inherently polyamorous or inherently monogamous people. Whether or not you can practice polyamory depends on 5 things: awareness of polyamory, willingness to break social norms, how you get your sense of security, how much energy you have, and connections with people you resonate with in a romantic way.
awareness of polyamory
I daydreamed about having multiple romantic relationships from the time I was a little kid, but I didn't know that it was possible until many years later. I was 24 when I realized that ethical non-monogamy was possible and there were people who did it. My first polyamorous relationships were long distance because I had never met anyone local who I knew to be polyamorous.
willingness to break social norms
Breaking social norms was already normal to me, having rejected sexism and looksism, but it was not something I could do whole-heartedly because at the time I was married to someone who was very worried about what people would think. Not being able to be out ate at me. I did come out to my bioparent P, who treated my visiting lover the same as my spouse - but less than a month after that, P moved to another state so I still had no local people I was out to. My next few relationships were local and they were all out, which was a huge relief for me.
how you get your sense of security
My sense of security held me back in a lot of ways, because my first romantic relationship was a monogamous marriage and my securities had been built on a set of rules. I thought rules were how you built security; I had never witnessed any other model. We practiced polyamory for about 2 years with this makeshift rule-based model. As the rules failed to make me safe from hurt and failed to protect my spouse from fear, I shifted my marriage to an uncommitted lover relationship. This was partly because the rules that made it a marriage did not work for me any more, and partly because in my view of marriage if you don't have similar goals in life then you shouldn't be married and my life goals were no longer similar to my ex's. That didn't last because when my ex looked for an additional person to date, they found a monogamous person and promptly dumped me for that person.
After that I built my sense of security on my ability to recover from damage and maintain boundaries. I set boundaries for my safety rather than my security (for instance, requiring safer sex practices for certain acts with me, rather than for the relationship to continue). To set a boundary I considered what could cause me damage and how it could be mediated with the least interference with the other person's will. An example would be who my lover dates. I do not control the other person's choices, but I do control mine. So if my lover dates someone who I feel is damaging me directly or indirectly in a way that I cannot handle, I will put distance between me and my lover until I am no longer so damaged. I will inform them ahead of time so that they know what my action will be and can adjust if they wish, but I will not expect them to or try to convince them to. This has only happened once (after a first date), and after I told my lover what I was feeling they examined their interactions with that person and found that they were bad at consent and thus no longer desirable for dating.
Nowadays I put my security partly in my ability to recover and maintain boundaries, and partly in my loveweb -- my friends who I invest in. If I were to break up with someone, it would be painful (maybe devastating), but I know that I could rely on my friends to help me get through it, and eventually my ex-lover would be one of those friends. I do not emotionally invest in romantic relationships that will not be lifelong friendships (except maybe for Aurilion, because I have a weakness there). If I feel that they wouldn't stay my friend if we broke up, I won't date them because that makes me feel like they only want part of me and a very minor part at that.
how much energy you have
Next need is energy. I once broke up with three people at once because I did not have the energy that it would take to maintain those romances any more. It was almost too late: [TW: depression, suicidal thoughts]shortly after that I went into the worst depression of my life, where for three months all I could think about, every waking moment, was wanting to die. It took citalopram and at least a year to get out of that. Then once I emerged from depression I realized how bad my ADD was and began trying to get help -- which took at least 8 months. During those months I had no extra energy because I had to throw all of it into my schoolwork just to maintain that. I spent many days in unproductive hyperfocus and many days in panic and stress to the point of crying uncontrollably. But once I finally got medicated, I had energy! I felt alive! I could do things! I was still terribly stressed about money and school, so not all was well, but I had more ability. And I started actively looking for an additional person to date, because I want that in my life.
connections with people you resonate with in a romantic way
The first month of looking was fun -- then it rapidly became miserable. I couldn't find anyone at all who seemed both akin to me and available. After three months I decided to stop looking, since after all I have never met a love by searching for them (they have all found me). I do keep looking for new friends, but have met a lot of failure in that area as well. There have been a few people who I thought I might be interested in romantically, but nothing came of it. This is where I am now, a year after I gained the energy. I have the awareness, willingness, security, and energy, but not the connections. I yearn for them. Topaz suggested that I do more activities that will allow me to meet new people, which is a good idea except that that is SO HARD when my car is fragile and I have little money for gas and have no one to help me motivate to go by going with me -- it takes like 50 points of energy and it is likely to only give me back 20. If I met someone amazing it would probably give me 100 points, but that certainly not something I can count on.
I still consider myself to be practicing polyamory, because I do not structure my relationship in a monogamous way or use monogamous rules. I actually identify as a relationship anarchist (a sorta-kinda subset of polyamory), because I do not decide which relationships get the most time, energy, or other resources; I let the situation lead me. I deliberately invest in my friendships, which may move in and out of romance based on the situation. Kylei is someone who I would definitely be dating if they were available, but so many parts of the situation make it almost impossible. Maybe next year I will have so much extra energy from finishing school that I will be able to spend the extra doing lots of the driving and planning, which is what it would take to make the situation work. As it is, there are romantic parts to our friendship, but we do not spend enough time communicating for me to feel romantic in a continuous way.