Your husband has been supportive in you having a boyfriend and you're saying he isn't allowed another woman to love him?
...Or are you saying you want a female to join a triad with you and your boyfriend, whilst your husband finds his own other women separate from you?
I'd say the second one certainly makes more sense and that maybe the way you worded it just confused me to think the first way... But I have read from a lot of people who actually believe in the first. To me, it isn't very poly at all. But everyone certainly has different levels to their own poly description.
Welcome to the site anyways.