My answer will really reiterate the general consensus - I do believe that poly can work. I do believe that it is hard work. And I do believe that there has to be a genuine, honest part of you that believes in it to make it work.
I have been in my poly relationship for just over two years. Most of our arguments are related to poly. In the early days, they were jealousy arguments. Then, they became expectation arguments. These days, when we argue, it tends to be because we are miscommunicating. For me at least, it has evolved and improved over time.
I have had many moments where I have questioned whether poly is 'right' for me. The thought of monogamy petrifies me these days. I just can't trust that relationship model.
Have you thought about the reason you want to be poly? I haven't read your background posts yet, so I don't know the details of your situation.
When things get rough for me, I remind myself of my core values:
1. I don't believe in ownership of a partner
2. I enjoy my own personal freedom
3. I don't trust that monogamy works - I would rather deal with the pain of poly than the pain of being cheated on
4. I want to grow. Poly helps me take insecurities and face them, grow and become stronger.