I've been in a triad for 6 years now, my married partner and I have been together for 11 years and we were always poly-amorous. We are a family of men, we all three live together and function as one unit. I think adding a third works best when it happens naturally for both men in the original coupling and both are into the idea. Sexually, there is a ebb and flow in our relationship, but there are two key things that keep us going. No long-term jealousy (everyone has moments of jealous, but you move past it) and being open and honest. All three of us have other men in and out of our lives and bedrooms. Some we play with together, some 2 on 1 and some just one on one. I have a boy on top of my triad relationship (love you mindtrip) who fits perfectly because he too understands the difference between love and fucking another pig. Insecurities and jealousies are hard on a couple, but they will absolutely destroy a triad.