How to go about the topic of inviting others into our sex life?
Long story short my (29f) fiancé (30m) and I are very secure in our relationship and have been for over 3 years now. A couple days ago I expressed a dream I had where I was in the middle of a threesome with him and another man. He had mentioned that it being a MMF situation, he would prefer it than another female. He also explains he loves the idea of me being dominated between himself and another. Our conversation didnt last long but I have been thinking about it non stop as to how i should bring this up again. I dont believe it would be a sensitive topic but i also dont want to keep talking about it and cause him to believe i am unhappy with him. Im truly happy, I just know i deeply enjoy the kinky side and would like to branch a little more while he is still my main partner and involved. I do have some boundaries in mind personally as to who we would bring into our relationship. I wouldnt want it to be someone who is a constant or someone who may catch feelings for either of us.
My question would be, how do i go about this topic seriously and not hurt our relationship?
I also would like to hear about others personal experiences. I never used to be the type that would ever consider non monogamy, but now I am in the most healthy relationship i have ever experienced and we are both learning more about ourselves i would like to explore with him.
Thanks in advance!