Sorry if this sounds blunt or old fashioned. I have been married for 22 years to a wonderful woman. She experimented early on with a bisexual relationship and threesomes before we met. I was very forthright and when we got serious, I explained that I simply did not want to share her affection with anyone else. While we had our tumultuous early years, it became obvious that she also wanted a monogamous relationship long term and was satisfied with what we had created together. We married and have 2 wonderful girls, who have both professed to being bisexual in nature. I am fine with it, as is my spouse. I truly believe it all comes down to being honest in your expectations of the relationship. However, I never found the prospect of even a F/F/M being interesting in the least so I am probably an outlier who is just straight by preference.