My Fiance can't accept my daughter's ADHD

My 9 year old daughter has ADHD. I have her on meds and in behavior modification therapy. Her tantrums have almost completely dissappeared but she still has behavior issues and getting easily angry and upset over the smallest thing. Especially in the morning and late evening (before and after meds). Most of this negative behavior is directed at my fiance who believes she is just being a sh**. He is frustrated and tired of the drama and has come to dislike her immensely. I try to make him realize that you can't use standard disciplinary actions with a child with ADHD but he hasn't read "Parenting Children with ADHD" or listened to "Total Focus" like I have requested. I have a 7 year old daughter who loves him and he loves her. He shows the 7 year old much love and attention and is condesending and generally mean to the ADHD child. He has agreed to read the book and go to a therapy session with us. Should I just give up and leave if he doesn't come around and understand? I really think it might be easier if it was just the 3 of us again. Any suggestions as to how to get him to realize she's not a bad kid, but that the ADHD makes her seems as though she is?