Well, we both always designed without collaborating, both being the only designer in our families. But we both bring these design skills, and so we collaborate.
An art teacher friend of mine has an architect husband, not a dual, a good match though, and they were at odds with home design all the time and usually it took her giving in, as arriving at a compromise most of the time was too difficult. With two designers, its harder. Though I think its IMPORTANT for the husband to give in to the wife on this, and I think her husband was wrong here. He is a good guy in plenty other ways.
Yes, I would say in general home design is the wife's domain. Of course, you agree, when the husband is better at this, as in an architect, or more interested, his input is important. My EII friend with her SLE husband - she let him do it, MOSTLY, for compelling reasons. But there was the time he picked out kitchen backsplash tile without her - and installed it while she was out for the day - she got home as he and his buddy (that she did not like) were finishing the job. And that was her limit. She called me and asked me to help her PULL IT ALL OFF" quick, while it was wet and while he was out on a call... and I did...