Once, another copywriter asked me how I was getting along with my art director. I told him we worked well together. Sometimes we got in some arguments about the work, but we were always respectful of each other's opinions, and were quick to apologize to each other if the debate got too heated.
I took some pride in being able to argue with my art director. I felt it showed we both cared about the work. And to some degree, there might be some truth in that. But his reply made me see things differently. He simply said, "I don't want to have to fight with my art director."
I've since found, that if I'm arguing with my partner, it's either because one of us is being stubborn (which can be remedied). Or because we have drastically different tastes (and if you don't respect their taste, you should consider a change).