thoughts on threesomes within a relationship?

I am currently with a man 
Would like to experiment with a woman,with him or even without him. But completely with his consent. 
I'm not too sure if he would be comfortable or into it. I never would force anyone to feel  obligated to do something like this for me. 
I'm bi-curious, always have been. It has always been a question mark for me. I've made out with girls when I was single but I never had the chance to take it any further. 🌈