What a nice story about your personality and sexuality meshing with another person's.
Question about it that I have is: why do you think that you will ~have to~ stop being sexually promiscuous for him? What if his choice was for you two to be even married but in an open relationship that allows other people to still enjoy you and him to fuck others too?
There's the hetrosexual type version "hot wife" of a sexually promiscuous woman in a marriage with a man. In my life, I was/ am the "hot husband" version originally with women and now only with men. And I don't expect monogamy for my partner just as she doesn't have any doubt of my promiscuity with men. We're totally monogamous in emotional and romantic ways but absolutely not in physical and sexual arenas.
Just asking because promiscuous sexuality doesn't mean that you cannot have a loving relationship and bond with another person. It just means that the other person has to be open and understanding about your relationship.