If he's willing to discuss it, it may be worth exploring why he cannot do it. Make it clear that you are only "just talking;"--he is not agreeing to do anything, only agreeing to talk, and to listen. If found that my mono wife was more willing to engage in conversation if I made clear, and repeated whenever she started to object to what I was saying, that we were only talking; we were not agreeing to do anything differently than what we had been doing (which is a traditional mono marriage).
I'm still not where I want to be, but at least we can talk to each other, and by taking the scary threatening thing of doing off of the table (at least for now), she felt safer talking to me about what she thought and felt, and about listening to what I had to say, and at least starting to think about it, rather than flat-out reject everything out of a self-protective, fearful reflex.
Baby steps, if you want to try to keep your marriage together. You may reach a point where you find that the gap between you and your husband is simply too wide to bridge, and then you have a difficult decision to make.