I’m afraid I like the idea of poly-relationships but can’t feel comfortable in one. I never identified with monogamy, I find it toxic, specially bc of the lack of communication, but now, being in a monogamous, loving relationship, with a patient and caring partner, I’m having trouble with dealing with my own insecurities and jealousy - we’ve been together for several months. (She’s the only one who has other partners, I don’t actually get interested in other people).

There’s a lot here to unpack. You say you can’t feel comfortable in a polyamorous relationship, but you’re also unhappy being monogamous. It sounds like the issue is deeper than relationship style, and has more to do with the insecurities and jealousy you know you have. 

Without knowing more about the situation, my best advice would be to see a poly-friendly therapist (you can find a list of them here) to work on those issues of insecurity that are keeping you from a happy, healthy relationship. If you can’t afford a therapist, you can try some DIY therapy with mindfulness practice and self-help books and online programs that fit your needs. For me, reading Daring Greatly was really helpful and healing - find what works for you.

And, as always, communication is so important. Part of communication is about speaking into the situation - talk things out honestly with your partner. And the other part is listening - doing your best to hear and trust her when she says that she does care about you.

Finally, I can’t let this go without making one crucial clarification. Monogamy is not inherently toxic, nor does it necessarily come with a lack of communication. It can seem like people practicing polyamory talk more about communication and work more explicitly on healthy communication practices, but there’s nothing preventing monogamous folks from doing the same, and all the things that poly people do to make their relationships work can be done in monogamous relationships. True, monogamy doesn’t work for everyone - but that doesn’t mean it’s not a totally valid, fulfilling, healthy way to live.