The most difficult part of polyamory in my experience, as someone who used to be polyamorous with my soulmate, and still might be again in the future, was the feeling of "he gets to experience X with the metamour, and I'm alone, I feel abandoned and like my needs are not being fully met while he satiates his every urge with his multiple partners and as a result, doesn't have the time or urge to have cyber sex with me as often as I would want and as often as he probably would want if he didn't have a physical sexual partner easily accessible". It was compounded by the fact we were long distance and his metamour was in the same country as him.
A stable triangle polyamorous situation is obviously the situation where everyone feels equally fulfilled by the situation as everyone else, but the V shaped polyamorous situation is more difficult, and I am still not fully happy with it, even though in theory I support it and I do feel secure in my partner's love for me. It's not a lack of love, it's a lack of quality time and a lack of physical touch that I feel polyamory takes from me. And I don't think I'm capable at this stage of a triangle polyamorous relationship because I can't make myself fall in love with a metamour unless it happens organically.
I guess what matters in each relationship is what you expect your partner to provide you. Do you want them to be able to meet your sexual needs? Do you want them to be there for you when you are lonely, to make sacrifices for you? If that's the case and polyamory takes away from this ability to meet your needs, is it right for you?
I still don't know exactly where I stand. I guess over time we will work it out with lots of communication.