I have to agree with the others. Poly should not be something you explore to fix something in the relationship. My bf and I are exploring the idea because while we love one another very deeply and know we are spending the rest of our lives together we also know that there is room in life for other loves and other experiences. It has been very eye opening, very truthful and full of love. Its amazing the things you think will be the hardest on your relationship somehow turn out to be the best idea there has ever been!
it sounds like the relationship as a whole isnt in the best form right now and that should be worked on before entering into other relationships. Especially if you feel you might be seeking out other relationships solely because you are not happy in your current one. Then its more of just replacing your partner than having a poly outcome.