On the half a realashionship comment I think I may be able to clarifly as I'm in a similar situation, albeit less complicated as its onlly the two of us talking about my girlfriend taking another partner. He is Mono and only seeing you. In his mind you are the only person he needs, you are on the level of family, probably higher even. He probably sees you caring about him on the same level you care about someone else as cheating, worse because there is sex involved. For mono people like myself partner or lover is one of the highest levels of realashionship and it is reserved for oly one person you care about above all else, at least in such a way. He sees himself as only being able to be half of what you need to be happy. He sees your husband as being what he cant be to you. It's painful and hard to explain but thats my attempt. I hope its helpful to you.
If it doesn't make sense I apologize, I'm nit good at articulating myself, worse still at explaining emotions
Last edited by Riunin; 11-11-2009 at 08:09 AM.