This happened a week ago. I recent started dating my best friend of 3 years. I finally got the balls to ask her out and she agreed and its been going great since. There is a bit of a story there, but I will leave that for another time. She is pretty fucking kinky, as am I. We don't share a lot of fetishes, but we have always been happy to assist each other with them, even before we started dating. I have always told her that I wanted to try sex with a guy some day, and she always tried to get me to do it, but the stars just never aligned I suppose.
Fast forward to day one of our relationship as a couple. We know each other about as well as we are ever going to, so touchy subjects are not really a big deal to discuss. I have always told her that I would want a monogamous relationship if I ever "settled down" some day, and she was always the opposite, so this is clearly an issue. Before I asked her out I decided that there is no one I trust more, so I could get past the "open relationship" this as long as I was always involved, I told her that was a must, and she agreed on that.