A three way relationship

I have liked women all my life.. And at the age of 13 I met a guy that had such an impact on me. After all that I had been through in my life by that point I saw myself as ugly and unlovable. I have now known this guy for 18 years and been with him for 16 years. I have never lost my love for women. I presented him with a proposition... We have had threesomes and have even tried to explore the possibility of a family. I want him and a woman. And he is okay with it. But why is it so hard to find an honest female that can like us evenly and not try to break us up??